Textbook ISBN 978-981-14-7491-0 First Published 2020 Consulting author Giam Kah How PRIMARY 6 6001 Beach Road, #14-01, Golden Mile Tower, Singapore 199589. E-mail: [email protected] Printed in Malaysia by Percetakan Jiwabaru Sdn. Bhd. No. 2, Jalan P/8, Kawasan Miel Fasa 2, Bandar Baru Bangi, 43650 Bangi, Selangor Darul Ehsan. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying, mechanical, recording or otherwise, without the prior permission of Praxis Publishing Singapore Pte. Ltd. © Praxis Publishing Singapore Pte. Ltd. 2020 The URLs in this book were reviewed and deemed suitable at the time of publication. This cover has been designed using resources from Freepik.com, image by brgfx.
Contents LIVING THINGS AND LIFE PROCESSES Chapter 1 Adaptations for Survival 1 1.1 Factors that Affect the Survival of Living Organisms 2 1.2 Adaptations of Living Organisms to the Environment 4 1.3 Extinct and Endangered Animals and Plants 22 Chapter 2 Relationship among Living Things 26 2.1 Organisms, Population and Communities 27 2.2 Communities at Different Habitats 29 2.3 Roles of Living Organisms in Feeding Relationships 33 Chapter 3 Human Impact on the Environment 40 3.1 Impact of Human Activities on the Environment 41 3.2 Human Activities and Environmental Conservation 48 ENERGY AND THEIR CHANGE Chapter 4 Forms and Uses of Energy 52 4.1 Forms of Energy 53 4.2 Conversion of Energy 62 4.3 Alternative Sources of Energy 64 ii
Chapter 5 Force and Motion 72 5.1 Effects of Force on Objects 73 5.2 Types of Force 76 Chapter 6 Sound and Its Properties 86 6.1 Production of Sound 87 6.2 How Sound Travels 88 6.3 The Properties of Sound 90 6.4 Caring for Better Hearing Health 94 MATTER AND THEIR PROPERTIES Chapter 7 Classification of Matter 98 7.1 Pure Substances and Mixtures 99 7.2 Homogeneous and Heterogeneous Mixtures 101 EARTH AND THE UNIVERSE Chapter 8 Rotation of the Earth and the Moon 107 8.1 Rotation and Revolution of the Earth 108 8.2 Rotation and Phases of the Moon 111 8.3 Eclipses 114 STEM Activity 119 iii
Let’s Think Let’s Try! Let’s Scan What pupils already know Reflects what pupils have learned Challenges pupils with questions that promote higher-order thinking skills Presents extra information that is relevant to the concept learned What pupils would like to explore as they study the chapter Helps pupils to master their scientific knowledge and skills Provides direct access to the relevant information on the Internet by scanning the QR codes given A diagram to ‘map’ out all the concepts in the chapter An activity that engages in applying the knowledge of scientists, mathematicians and engineers Explain It Map It Out Provides direct access to extra questions by scanning the QR codes given Explains difficult terms used in the text Encourages pupils to find information and present their findings Let’s Find Out! STEM Activity Let’s Know More Online QuickQuiz Special Features Special Features iv
Chapter 1 What do I know about the adaptations for survival? 1. 2. 3. What do I want to know about the adaptations for survival? 1. Identify the factors that affect the survival of a living organism. 2. Explain how structural, behavioral and physiological adaptations help living organisms to survive in their habitat. 3. Describe the importance of habitat conservation to prevent living organisms from becoming extinct. Adaptations for Survival Animals need air, water and food. They live in a habitat and interact with other living things. What are the living and nonliving components that they need to interact with in order to survive in their living environment?
Everything surrounding a living organism is called its environment, which includes the non-living and living components it comes into contact with. These components are important factors that affect the survival of living organisms. Thus, all living organisms must be able to adapt to changes in their non-living and living components in order to survive. The non-living components that affect the survival of living organisms include temperature, water, light, air and soil. How hot or cold a habitat is affects the types of animals and plants living there. Many living organisms have special characteristics to adapt to the cold climate or hot climate. However, most organisms cannot survive in extreme temperatures. Temperature Rivers, lakes, rain and groundwater provide water for living organisms. Living organisms cannot survive without water. Water is important for activities such as digestion and photosynthesis. Water also serves as a habitat for some animals. Water Plants need sunlight to carry out photosynthesis. Without sunlight, plants and other living organisms that depend on plants for food will not be able to survive. Animals such as turtles and lizards need sunlight to keep their body warm in order to get energy. Light Organisms need oxygen for respiration. Plants need carbon dioxide for photosynthesis. Without air, living organisms cannot survive. Air Most plants get water and minerals from the soil. The type of soil such as sandy soil, loam and clay determines the kind of organisms living in a soil habitat. Soil Factors that Affect the Survival of Living Organisms 1.1 2 Hands-on Science Primary 6
The living factors that affect an organism’s ability to survive in an environment include the availability of food and the presence of other living organisms. Living organisms get energy from a variety of food to survive. The types of food and the amounts available in an environment determine the types of animals that live there. For example, pandas can only survive if they live in an environment that has bamboo. Availability of food Presence of other organisms Adaptations for Survival Chapter 1 3 Plants are producers. They produce their own food. However, they have to compete with each other for sunlight, water and minerals from the soil to make food. The plants that grow in an overcrowded area usually do not grow well and some may die due to competition. Plants Animals that eat plants or other animals are called consumers. Animals that live in the same habitat will compete for food among themselves. Stronger animals that can get enough food will survive, whereas weaker animals that are unable to compete will have to move to other places or die of hunger. Animals When plants and animals die, they become food for other living things such as bacteria and fungi. They are called decomposers. They break down dead or decaying organisms into simpler substances that are returned to the soil as nutrients for the use of producers. Some of these decomposers cause diseases which can spread quickly when the decomposers multiply speedily. This affects the survival of other living organisms as some may die from the diseases. Bacteria and fungi
Adaptations of Living Organisms to the Environment 1.2 Hummingbirds have a long beak that allows for more effective reach into the narrow opening of tall flowers for nectar. Cacti have thick stems to store a large amount of water in any dry environment. Their stems are also used for photosynthesis. Sunflowers grow towards the Sun to get the maximum amount of sunlight for proper growth before they reach maturity. Penguins have thick skin with fat underneath to keep warm in cold weather. They also huddle in groups to stay warm. On top of that, the complex heat exchange system in their nasal passages helps them retain a high percentage of heat in their breath. Organisms live in different habitats such as deserts, tundras, oceans and grasslands. Organisms that live in these habitats have special characteristics to help them adapt and survive in their environment. Organisms survive if they can: • cope with physical changes in the environment such as temperature and light • get enough air, food and water • protect themselves from their enemies • reproduce The process that enables organisms to adjust to their environment in order to survive is called adaptation. Adaptations can be structural, behavioral or physiological. Structural adaptations are the physical features of organisms that help them survive in their habitat, such as the body covering and skin color of animals. Behavioral adaptations are the ways organisms behave or the things they do to survive. For example, polar bears hibernate in winter to conserve energy. Physiological adaptations are the internal responses of organisms to external stimuli, which enable them to survive in their environment. For example, snakes produce poisonous venom to capture prey or defend themselves. Can you identify the type of adaptations by the following organisms? 4 Hands-on Science Primary 6
Adaptations to Cope with Extreme Temperatures Animals and plants have amazing adaptations that help them live in environments with extreme temperatures. In Hot Environments The desert is a harsh environment. Organisms that live in this environment have to adapt to the extreme temperatures and situations with little or no water. Spine Hump The desert fox has large ears to release excess body heat to its surroundings. Some desert lizards stay in the shade during the day to prevent overheating. They look for food at night when it is cooler. Camels’ legs can kneel on hot sand due to the thick leathery patches on their knees. Their feet are padded to prevent them from sinking into the soft sand. Their hump stores fat that provides them with energy for long periods without food. Storing fat Let’s Think Camels can drink a lot of water at once. They can also survive for a whole week without water. In what ways can they conserve water? Cacti in the desert conserve water by not having any leaves. They have spines that prevent the loss of water. Adaptations for Survival Chapter 1 5 Staying in the shade Losing body heat Conserving water
In Cold Environments Organisms that live in cold environments protect themselves from the low temperatures via different adaptations. Geese fly in a V shape when migrating. They migrate before winter arrives. They fly to a warmer place to escape from the cold and find food. Migration Trees go through a process called dormancy during the winter. In this process, everything within the plant, including energy consumption and growth, slows down. Trees shed their leaves because they do not need to make food in the winter. Therefore, less energy is required to keep their leaves. Dormancy Having thick body covering and an insulating layer of fat The polar bear has thick fur. It has a layer of fat under its skin to keep its body warm and which acts as an energy store for slow hunting periods. It can swim and stay in ice-cold water. Hibernation Polar bears spend the winter sleeping. This is called hibernation. During hibernation, its heart rate, body temperature and breathing slow down to conserve body heat and energy to cope with the cold. 6 Hands-on Science Primary 6
Adaptations for Breathing Air is important for living organisms. They need air to carry out life processes. Some organisms have special body feature adaptations to breathe in air dissolved in water or atmospheric air. Breathing in Air Dissolved in Water Most aquatic animals have gills that help them to breathe in oxygen dissolved in water. When water passes through the gills, oxygen is taken in and carbon dioxide is released into the water. The water then passes out through the gill opening. Examples of animals that breathe with gills are prawns and tadpoles. A tadpole uses its skin to take in oxygen that is dissolved in water. Its skin is thin, soft and must be kept wet all the time. Other examples are flatworms and salamanders. Gills Skin Crabs are water-living animals. When they are in water, their gills become moist, and absorb oxygen from the water. When they are on land for short periods of time, the gill chambers have enough stored water to keep the gills moist. When the oxygen in the atmosphere comes in contact with the gills, it enters the body of the crab. Gill chambers Crabs have gills that are attached near the base of the legs and are enclosed by gill chambers. Adaptations for Survival Chapter 1 7
Breathing in Atmospheric Air When a dolphin comes to the water surface for air, we can see a spray of water blowing from its blowhole. It breathes out first then breathes in fresh air. It can also hold its breath for several minutes. Aquatic mammals such as whales and dolphins have lungs to breathe in air. They cannot breathe like fish when underwater because they do not have gills. They breathe through a blowhole at the top of their heads. Blowholes Blowhole Air tube Air tubes We see mosquito larvae float on the water surface because they take in atmospheric air through breathing tubes that extend from their body. Air bubbles Aquatic insects have adapted legs, wings or hairy bodies to trap air bubbles. They breathe in the air from the bubbles while submerged in water. For example, the water spider lives underwater and uses its web to create an underwater sac that stores air bubbles. Nostrils Special nostrils When a crocodile dives, it shuts off its nostrils. It surfaces to take in air. Since its nostrils are on the top of its snout, it can breathe without coming out of the water. Orchids can adapt to life high above the ground. They have aerial roots that hang in the air to absorb moisture and nutrients from the air. Aerial root Breathing root Mangroves grow in soil that has limited air. To cope with this condition, mangroves have breathing roots containing pores that grow above the soil to obtain oxygen from the air. Breathing roots / Aerial roots 8 Hands-on Science Primary 6
Animals move on land, in water and in air. They need adaptations to move in the habitats they live in, such as rainforests, grasslands or oceans. The adaptations are for: • overcoming problems when moving over different surfaces or obstacles • obtaining food or catching prey • protection, to escape from danger or predators Moving on Land Animals that live on land move in different ways. The orangutans are found in the rainforests of Borneo and Sumatra, Indonesia. They live in trees. They have long and strong arms to carry their heavy bodies from branch to branch. They also have strong and short legs with flexible hips to help in climbing. Adaptations for Movement Orangutans are the world’s largest mammals that live in trees. They are great apes found in Asia. However, they have become extinct in some parts of Asia because their habitat in forests has been used for oil palm plantations. Horses have hooves which are the hard parts on the bottom of their feet. They allow the horse to run on hard or soft surfaces and move quickly to escape from predators. The tail is used to get rid of insects that could bite the horse. It is also used for balance. Snakes move in a variety of ways, such as sidewinding or moving forward like a caterpillar. It depends on the type of surface they are moving on. Some have a long thin body with scales that help them to grip branches. This helps them to glide forward. Hoof Adaptations for Survival Chapter 1 9
Moving in Water Some aquatic animals such as sharks have a streamlined body shape to enable them to overcome water resistance so that they can swim efficiently in water. Narrow end at the head Broad at the center Narrow end at the tail Many aquatic animals have special body parts such as fins, swim bladders and flippers to help them swim in water. Fins are located at different places on the fish to help it keep balance, move forward, make turns, keep an upright position or stop. A swim bladder is a balloon-like internal organ that contains gas. A fish can move up or down through a water column by changing the amount of gas in the bladder. Fin Fins Work in groups to look for information about the following to share in class. (a) List three other examples of animals that have different adaptations (structural, behavioral or physiological) when they move in water. If the examples you suggested are animals that can live both on land and in water, list the adaptations of movement when they are on land. (b) For each of the examples, describe how they breathe in water or on land. Let’s Find Out! Flippers Sea turtles have flippers that help them to swim long distances. Flippers allow them to paddle in water using less energy. 10 Hands-on Science Primary 6
Moving in Air Let’s Think Butterflies are insects that have beautiful wings. Other than serving the purpose of flying, what are the other structural adaptations of the wings that help them survive in their environment? Most flying insects have two pairs of wings. Their wings are small compared to the size of their bodies. Thus, they beat their wings very fast to keep themselves in the air. Birds have a streamlined body shape that is narrow at the ends and broad in the center. They have a bony skeleton in their bodies. Their bones are very light and some of them are strong but hollow to reduce their body weight. Flying animals have wings to help them move in the air either to look for food or escape from danger. The feathers overlap each other in a special way. The feathers are light. They aid in flight, waterproofing and help to insulate the bird from the cold. The bee beats its wings to stay in the air before reaching the flower to get nectar. Adaptations for Survival Chapter 1 11
Adaptations for Obtaining Food Predators hunt other animals for food to survive. Most of them are carnivores. They use different hunting strategies and tools to catch their prey. Lions have sharp retractable claws that make it easy for them to kill their prey. Their sharp, pointed teeth help them to shred and tear the meat they eat. Crocodiles have short limbs and a large, flattened mouth. Their eyes, ears and nostrils on top of their head allow them to keep almost their entire body underwater, and to remain still and wait in the water while hunting their prey. Once they catch their prey, they bite off large chunks of meat and swallow them whole. Eagles have good vision to easily spot prey from far above the ground. They have powerful claws on their feet to catch and hold onto their prey during flight. Their deeply hooked beak with sharp cutting edges, helps to tear and eat the flesh. Cheetahs have muscular legs that allow them to run at a very high speed to chase their prey. They also have sharp claws to catch and hold their prey such as deer. This enables them to attack alone instead of in pairs or in groups. What are the other structural adaptations of cheetahs that you know? 12 Hands-on Science Primary 6
Chameleons have a long and sticky tongue as their weapon to snag insects. They shoot their tongue out towards their prey to capture it, then bring it back to their mouth and swallow it. Herons have long, pointed beaks to hunt frogs, fish and other small animals. They stalk or follow their prey quietly. They wait for the right time to quickly strike their prey, and swallow it down their throat. Owls can turn their heads as much as 270 degrees to follow their prey as it moves. The color of their feathers helps them blend into their environment, making them unnoticeable to their prey. Owls are active at night. They have good eyesight and sensitive hearing to detect small prey such as rats making rustling noises among the leaves in the dark. In addition, they fly silently to enable them to approach their prey quietly. When they come near the prey, they grab it with their sharp claws. Adaptations for Survival Chapter 1 13
Army ants hunt prey in groups. They move across tropical forests and eat any animal, such as crickets, lizards and scorpions. They kill and eat their prey by tearing it apart with their scissor-like jaws. What are some other animals that hunt in groups? Carnivorous plants such as sundews have leaves that bear sticky hairs to trap insects such as flies. They attract prey by producing nectar. When the fly lands on the plant, it curls and wraps up the fly, then digests and absorbs its nutrients. What other carnivorous plant have you learned about? Most spiders trap insects using a web. They first bite and inject venom into their prey. The venom turns the prey’s insides into liquid, which the spider sucks out from the body later. Some spiders can change their colors or hide themselves in flowers, and wait for the right time to catch their prey. 14 Hands-on Science Primary 6
Adaptations for Protection You have learned a few ways of how animals and plants protect themselves in Primary 2. Can you list them? Below are some of the adaptations of how living organisms protect themselves. Tortoises cannot escape fast from predators, thus they have a body covering such as a thick and strong shell to help keep them safe. A tortoise can hide its head and legs inside its shell for defence. Squid protect themselves by letting out a black ink that darkens and clouds the water, making predators unable to see them easily. At the same instant, they swim quickly away from danger. They can also camouflage to appear almost transparent to blend in with their surroundings. Body covering Camouflaging Mimicry Some animals use the tactic of mimicry to confuse predators. They look, smell, act or sound like other animals. Therefore, predators learn to avoid them. The bumblebee moth resembles a bumblebee. Birds keep away and do not eat them because they are scared of getting stung. This is the way that animals play hide and seek to help them survive. By changing the color and pattern of their skin, they can blend in with their surroundings. With camouflaging, they can hardly be seen by predators and this protects them from enemy attack. At the same time, this helps them to catch prey easily. Do you notice there is an animal on this plant? What is the animal? Adaptations for Survival Chapter 1 15
Sharp spines Hairs, strong smell, unpleasant taste and poisonous Sensitive leaves Some plants such as dwarf thistle have sharp spines on their leaves. This protects them from grazing animals. The flowers have short stems, located amongst the prickly leaves, that are also well protected. Ground ivy has lots of hairs. It has an unusually strong smell in its leaves and tastes bitter. All these factors keep grazing animals away from eating them. Livestock can be poisoned by this plant. Mimosa pudica is a sensitive plant. When touched, its leaves fold in rapidly. This rapid folding makes the plant appear smaller, while some parts of the stems have sharp spines to put off insects or herbivorous animals from eating them. Work in groups to present the following information gathered to share with your friends in class. (a) List three other adaptations for protection in animals and plants. (b) (i) Classify the adaptations as either structural, behavioral or physiological. (ii) Suggest three examples each of animals and plants for each of these adaptations. (iii) Explain how these animals and plants protect themselves with the adaptations. Let’s Find Out! 16 Hands-on Science Primary 6
Adaptations for Reproduction Animals and plants reproduce to ensure the continuity of their kind. Animals have to mate to reproduce. There are different ways for animals to find and attract their mates. Some animals have a colorful body covering. The peacock spreads and displays its tail feathers to attract the peahen. Females usually select males with larger and more colorful tails. Colorful body coverings Mating behavior The males of some animals fight with each other for access to a female mate. While fighting, the female chooses which male to mate with by observing the male competition. A male frigate bird changes its appearance by blowing up its red throat sac to attract the attention of a mate. The female will go to the male with the largest throat sac. Guppies attract mates by performing a sort of mating dance. The males use their tails to emphasize the way their bodies twist and turn. Female guppies are attracted to brightlycolored males. Adaptations for Survival Chapter 1 17
Can you recall how flowers are pollinated and the types of dispersal methods you learned in Primary 5? Do you know the structural adaptations for pollination and seed dispersal in plants? Pollination Seed Dispersal • The fruits dispersed by animals are scented, brightly-colored, fleshy and sweet. For example, bright red berries are easily found by birds as food and they help in dispersing the seeds. • Seeds such as burdock have tiny hooks that allow them to hold onto the fur of animals when they pass by. 1 Animal Dispersal Berries Burdock Some plants are pollinated by animals such as birds and insects that transfer the pollen grains from one flower to another. Plants that are pollinated by animals are often brightly-colored and have large petals. They also have a sweet smell to attract animal pollinators such as butterflies, bees and moths to collect the nectar from them. When they are collecting nectar, they help to transfer the pollen for fertilization to take place. 1 Another way of plant pollination is by wind. The wind picks up pollen from one plant and blows it onto another. The plant pollinated by wind is usually dull-colored, unscented, and has small or no petals since it does not need to attract animal pollinators. After fertilization, the plant produces fruits with seeds. The seeds can grow into new plants if they are well-dispersed. What are the characteristics of fruits and seeds that can be dispersed through various ways? 2 18 Hands-on Science Primary 6
2 Wind Dispersal The seeds dispersed by wind are usually small and light. They have a feathery structure that enables the wind to carry them far away to land elsewhere. Some have a parachute-like structure to keep them afloat. Examples of these are dandelion, shorea fruits and maple seeds. Dandelion Shorea fruits 3 Water Dispersal Plants that live near water or in water rely on moving water to disperse their seeds. When the seeds are released from the pod, the seeds will float on water and be transported away. For example, lotus seeds. Fruits dispersed by water such as coconuts are light and have fibrous husks that contain air spaces to keep them afloat on water. Coconuts float on water until they reach land. 4 Explosive Mechanism Some fruits have built-in mechanisms that allow them to split by themselves. Rubber trees have pods that contain seeds. When the seeds are ripe and the pod has dried, the pod bursts open and shoots out the seeds. Let’s Think Other than the characteristics given in the text, discuss and list two examples of fruits or seeds with other characteristics. Relate their characteristics to the method of seed dispersal. Lotus Seed pod Coconut Maple seeds Rubber seeds Adaptations for Survival Chapter 1 19
Adaptations for Obtaining Sunlight Leaves absorb sunlight for the process of photosynthesis in order for plants to grow well. Therefore, it is important that plants can grow high up and their leaves are well-positioned to receive the most sunlight. How do land plants obtain sunlight? Creepers such as watermelon plants and carpet grass spread on the ground. Their shoots spread out of the main stem to get sunlight. Twining stem Shoot Some trees have strong woody stems and branches to hold the leaves. They grow tall, and the leaves spread out to capture the maximum amount of sunlight. Plants that have soft stems are not able to grow upright. They climb up trees or creep along the ground to reach for sunlight. Such plants are climbers and creepers. Climbers cling onto plants that have strong stems, walls, fences or other supports with twinning stems, leaf tendrils or clasping roots. Cucumber plants climb up the support with tendrils in spiral form. They will wrap around anything they touch to climb up for sun exposure. Morning glory twines around a support with twining stems that climb up for sunshine. Tendril 20 Hands-on Science Primary 6
How do aquatic plants obtain sunlight? Aquatic plants have adapted in a number of ways to cope with their environment in obtaining sunlight. Sunlight passes through water. Some plants such as seaweed or algae grow completely underwater. They have air spaces in their leaves and stems that help the plants to stay upright in the water to get sunlight. The water hyacinth has bloated air-filled hollow leaf stalks. They trap air that provides buoyancy to the plant to float on water to gather sunlight. Bloated air-filled hollow leaf stalk The water lily is a floating plant. It has broad, flat, and waxy leaves that float on the surface of the water, enabling it obtain the maximum amount of light. Adaptations for Survival Chapter 1 21
In the natural world, animals and plants that are able to adapt well to the habitat they live in are most likely to survive. However, environmental changes such as climate change have an impact on the survival of animals and plants. They either adapt and survive, move to other places or die. Many living organisms no longer exist or have become extinct because they could not adapt to the change. Today, many more species of animals and plants are in danger of extinction or endangered. There are so few of them now.They are facing the threat of extinction due to human activities such as excessive deforestation for development and illegal hunting. As a result, these wildlife have lost their habitat and and may totally disappear in the future. Some of the examples of endangered animals are tigers, pandas and orangutans. The Tasmanian tiger with stripes on its lower back has been extinct since 1936. It is believed that hunting by humans contributed to their extinction as well as competition with other small predators. The woolly mammoth looked much like an elephant except that it was covered with fur to keep itself warm in its habitat and its curved tusks were long. It disappeared 10,000 years ago due to the loss of its habitat through climate change and hunting by humans. The dodo is an extinct flightless bird, and we can only see its model in the museum or through varied illustrations. The bird was hunted to extinction by humans and their domestic animals. Extinct and Endangered Animals and Plants 1.3 22 Hands-on Science Primary 6
The Rafflesia plant is threatened due to human activities such as logging and land clearing in rainforests. It is important to understand that the key role of each animal and plant in their physical environment, is as a predator or prey. Without them, it can lead to excessive numbers of some types of organisms or it may cause a lack of food resources for some types of organisms. Losing one species can affect many others. Conservation of living organisms is important because it protects native plants, animals and humans, by creating a balanced and healthy environment to function in. We can work with scientists and local community groups on habitat conservation and extinction prevention in order to secure a better tomorrow for our next generation. Work in groups, look for the following information, discuss and share the outcomes with your friends in class. • What are some other extinct animals and plants? • What are some other animals and plants that are facing extinction? • What can you do about it? Suggest ways to protect and preserve the natural habitats of wildlife. Let’s Find Out! As Earth gets warmer, animals and plants that live in their natural habitat might not have a suitable place to live. We can help these living organisms by protecting and preserving their habitats. The number of tigers is decreasing due to illegal hunting. This happens because many parts of their body, especially bones, skin and meat are in demand to prepare traditional medicines which have yet to prove their claimed results. In addition, the rise of sea levels, which is an effect of climate change, is also destroying the particular habitats of tigers. Adaptations for Survival Chapter 1 23
The internal features of organisms that they adapt by adjusting to their immediate environment Behaviors or the activities the organisms do to survive in their natural habitat Fill in the blanks. Some words can be used more than once. 1. The factors that affect the survival of living organisms are , water, , air, , availability of food and the presence of other organisms. 2. The physical features and how organisms behave to help them survive are called the and adaptations respectively. When an organism adapts to the environment by changing its body temperature, it is called adaptation. 3. In an extremely hot environment, some animals stay in the during the day to prevent overheating. When the environment becomes cold, some animals to conserve their body heat. 4. Some aquatic animals use and skin to help them breathe underwater and some animals like dolphins use to breathe in atmospheric air. Plants such as mangroves have roots above the soil to obtain oxygen from the air. 5. Animals have different adaptations for in order to catch prey or escape from predators. Some animals also have good and sensitive . 6. Some animals protect themselves by changing their and pattern of their skin while plants have sharp spines, strong smell or for protection. 7. Some animals have a body coloring or special behaviors to attract their partner for reproduction while plants have different physical characteristics of fruit and seeds that serve as adaptations to help in their dispersal. Plants also have some features that help them to obtain for photosynthesis. 8. Some animals have become due to failure to adapt to environmental changes, so we must protect and preserve the wildlife habitat for animals. gills structural poison endangered soil movement mating sunlight physiological light colors eyesight temperature breathing extinct shade behavioral hearing blowholes hibernate colorful The process that enables organisms to adjust to their environment in order to survive Adaptation Behavioral adaptations Physical features of the organisms that help them to survive in their natural habitat Structural adaptations Explain It Physiological adaptations Let’s Scan Online QuickQuiz 24 Hands-on Science Primary 6
Map It Out • Staying in the shade • Losing body heat • Storing fat • Conserving water • Migration • Dormancy • Thick body coverings and fat • HibernationFactors that affect the survival of living organisms Extinct and endangered animals and plants • Spread-out leaves • Twining stem • Leaf tendrils • Spread on the ground • Air spaces in the leaves and stems • Bloated air- filled hollow leaf stalks • Broad, flat and waxy floating leaves Extreme temperatures Sunlight • Colorful body coverings • Mating behavior • Pollination by animals and wind • Seed dispersal by animals, wind, water and explosive mechanism Reproduction • Body covering • Camouflaging • Mimicry • Sharp spines • Hairs, strong smell, unpleasant taste and poisonous • Protection Sensitive leaves • Muscular legs • Sharp claws, pointed teeth • Good vision • Long and pointed beaks • Sticky tongue and hairs • Sensitive hearing • Using a web Obtaining food • Strong arms and legs • Hooves • Body with scales • Streamlined body shape • Fins, swim bladders and flippers • Light and hollow bones • Movement Wings • Gill chambers • Gills • Skin • Blowholes • Air bubbles • Air tubes • Special nostrils • Breathing Breathing/ aerial roots Adaptations for survival • Non-living components: Temperature, water, light, air, soil • Living components: Food availability and the presence of plants, animals, bacteria and fungi • Organisms become extinct because they cannot adapt to change. • Conservation of living things is important in order to protect them from becoming extinct. Adaptations for Survival Chapter 1 25
Chapter 2 What do I know about the relationship among living things? 1. 2. 3. What do I want to know about the relationship among living things? 1. Differentiate between organisms, populations and communities. 2. Describe the communities found in different habitats. 3. Identify the roles of various living organisms and the transfer of energy in a food chain and a food web. 4. Describe the importance of food webs. Relationship among Living Things Owls hunt rabbits as their source of food. Other than rabbits, they hunt other living things in their habitat for survival. At the same time, they may become a food resource for other stronger animals such as eagles. All these animals live in a habitat and interact with each other. What are their roles and how does energy pass from one animal to another?
2.1 Organisms, Populations and Communities An organism is a living thing. It can be an animal, a plant or a bacterium. It cannot live alone. There is a wide variety of animals and plants living together in the same habitat. A habitat is the home of living organisms. For example, a field is the habitat for dragonflies, earthworms and coconut trees. It is the place where the organisms reproduce and get food, shelter and protection. Let’s Think Why do organisms move in or out from one place to another? In the same habitat, we can find different kinds of animals. Each kind of these animals is known as a population. It is a group of animals or plants of the same kind, living and reproducing in a particular habitat. For example, butterflies make a population on a field. At the same time, a group of ants is another population on the field. The size of a population is constantly changing. It increases when reproduction happens and organisms of the same kind move in from another place. It decreases when the organisms die or move out to another place. Organisms that live in the same habitat Earthworm Dragonfly Butterfly Ant Coconut tree Relationship among Chapter 2 Living Things 27
Many populations that live in a habitat form a community. The populations of dragonflies, earthworms, butterflies, ants and coconut trees make up the field community. In a community, the populations live together and depend on each other for survival. They interact with non-living components such as temperature, light, water, air and soil to form an ecosystem. Population of coconut trees A field community consisting of five populations Population of butterflies Population of dragonflies Population of ants Population of earthworms 28 Hands-on Science Primary 6
The different populations in a community are interdependent for survival. Do you know how the populations in the field community depend on one another? Fields are open space covered with grass and small plants such as goosegrass and mimosa. Some plants depend on insects to pollinate their flowers or depend on other animals to disperse their seeds. When plants make food during photosynthesis, they take in carbon dioxide which is released by humans and animals into the atmosphere through respiration. The products of photosynthesis are sugar and oxygen. As a result, plants serve as food resources for plant eaters such as grasshoppers and snails. The oxygen produced is for the need of all the living organisms in the community. Besides plant eaters, there are some animal populations such as spiders and lizards that feed on insects or worms. Let’s look at how the populations in other communitites depends on one another for survival. 2.2 Communities at Different Habitats Garden Communities The populations in garden communities are much the same as those in field communities except that there are many types of flowering plants in the garden. Birds or fruit flies are attracted to plants with fruits and they disperse the seeds. What other populations of animals can you find in the soil? Stems and leaves provide food for animals such as caterpillars. The scent of colorful flowers attracts insects such as ladybugs that pollinate their flowers. Relationship among Chapter 2 Living Things 29
Pond Communities A pond is an aquatic habitat. The organisms either live on the land near water, on or in the water. The plants in a pond habitat provide food, oxygen and shelter for the animals. What are the populations found in a pond community and how do they depend on one another for survival? Plants such as hydrillas are totally covered by water. They are rooted to the bottom. They produce oxygen for aquatic animals such as fish and tadpoles through photosynthesis. Frogs and ducks can be found in ponds. Frogs feed on insects and ducks feed on plants. Ducks also eat frogs, fish and insects. Water hyacinths float on the water surface while water lilies are plants with floating flowers and leaves, but rooted at the bottom of the pond. The leaves of the water lily provide a place for frogs to lay eggs. Microorganisms such as paramecia and water fleas live in water. They provide food for aquatic animals. 30 Hands-on Science Primary 6
Seashore Communities Seashores are unique areas. There are different types of shores such as sandy shores and rocky shores. All shores have one thing in common—they are covered at high tide and uncovered at low tide. Therefore, the organisms that live in these areas have adaptations that help them to survive in this constantly changing environment. Other than the organisms shown in the pictures below, snails, seaweed, clams and some insects also live in this community. Coconut husk Coconut palms grow towards the sea on the seashore because they disperse their seeds by water. The coconut husk can float in water and protects the seed from water. Starfish attach themselves to rocks so they do not wash out with the tides. They feed on clams and mussels. Hermit crabs hide under the sand during low tide and come out to hunt for food when the tide returns. Often, they hide under loose rocks. They curl their bodies inside empty shells to protect themselves. They eat anything that they manage to catch. Mussels hold in moisture by closing up during low tide. They attach to rocks so they are not washed away by the waves. They feed on plankton which are free-floating in water. Relationship among Chapter 2 Living Things 31
Tree Communities A swamp is a wet, soft land that is covered with forest. It is a muddy area during high tide. It provides a habitat for mangrove trees. Animals such as mudskippers, crabs, birds, snakes and crocodiles live in this area. The picture below shows the organisms that live in the tree community and mangrove swamp community. A tree can be a habitat for many populations of plants and animals. For example, ferns grow on trees. Animals such as spiders weave webs on trees to catch their prey. Some lizards also live in trees. Mangrove trees have prop roots that stick out of the mud to allow gas exchange in the oxygen-poor soil. The roots provide shelter for shrimps and prawns. Mudskippers eat in the water. They often bask on the mud or in mangrove roots. Birds build nests on trees. Rotting mangrove leaves provide food for crabs. Crocodiles eat crabs when they get older. Mosses that have no true roots grow on tree bark. Mangrove Swamp Communities Ants nest in trees. They usually catch their prey and move it back to the nest in groups. 32 Hands-on Science Primary 6
Green plants use the energy from the Sun to make food. They are called producers. Basically, animals and humans depend on plants and other animals for food. They are called consumers. Producers • Green plants have chlorophyll found in their leaves to trap light energy. • With this energy, they can make food through the process of photosynthesis. • They are the starting point of feeding relationships. Roles of Living Organisms in Feeding Relationships 2.3 You have learned about herbivores, carnivores and omnivores in Primary 2. Find out the following: • What are herbivores, carnivores and omnivores? • What are four examples of each class? Share your ideas and display the animals you suggested using a Venn diagram. Let’s Find Out! Consumers • Humans and animals cannot make food. They eat plants and other animals. They are consumers. • Consumers are classified into herbivores, carnivores and omnivores. A giraffe is a consumer that gets food from leaves, the producers. Relationship among Chapter 2 Living Things 33
Apple tree Squirrel (omnivore) Fox (omnivore) Lion (carnivore) Food Chains and Food Webs The relationships between producers and consumers can be represented using a food chain or a food web. Food Chains A food chain shows how one living organism becomes the food for another. It always begins with a plant as the producer. There are three food chains shown below. 34 Hands-on Science Primary 6 Grass Zebra (herbivore) eaten by eaten by Leaves Deer (herbivore) Lion (carnivore) What are the producer and consumers in this food chain? The fox in this food chain eats more than one type of food. Can you name them? Food chain 1 Food chain 2 Food chain 3 eaten by eaten by eaten by eaten by Food chain 1 starts with grass, which is eaten by zebras. Then, the zebras are eaten by lions. The grass is a producer, the zebra and lion are consumers. 34 Hands-on Science Primary 6
Food Webs A food web is made up of two or more food chains. This is because a living organism usually eats more than one type of food and it can be eaten by more than one kind of organism. Therefore, food chains are interrelated and they can form a food web in a community. This is a food web formed from three food chains. Can you identify these food chains? Work in groups. • Suggest three food chains for each habitat—field, pond, paddy field and forest. • For each food chain, suggest up to a maximum of four organisms. • Then, create a food web with pictures of the organisms for each habitat. • For each organism, state whether they are producers or consumers (herbivores, carnivores or omnivores). Share your food webs in class. Describe how the animals depend on the plants and other animals as food resources in the food webs. Let’s Find Out! Relationship among Chapter 2 Living Things 35 Fox (omnivore) Zebra (herbivore) Squirrel (omnivore) Plants Lion (carnivore) Deer (herbivore) eaten by eaten by eaten by eaten by eaten by eaten by eaten by eaten by Relationship among Chapter 2 Living Things 35
Transfer of Energy in Food Webs Plants trap light energy from the Sun to carry out photosynthesis. Plants as producers use the energy of the Sun to form sugar. The sugar may be used by the plants or stored in different parts of the plants. Giraffes are herbivores. They are consumers that eat plants. The energy stored in plants is passed on to the giraffes. However, giraffes are the prey of other animals. They are hunted by other animals as food. Leopards are carnivores. They are consumers too. They eat herbivores or omnivores. They are predators that hunt other animals as food to get energy. This is how the energy is passed on from one organism to another through a food chain, and eventually through a food web. In Primary 5, you have learned that plants produce food using light energy from the Sun. Do you know how this energy can be transferred from one organism to another in a food chain or a food web? 36 Hands-on Science Primary 6
Deer (herbivore) Lion (carnivore) The Importance of Food Webs A food chain or food web is important in a habitat. It shows the feeding relationships among different living organisms in the habitat and how energy is transferred from one organism to another. Any changes to the population of a living organism in the habitat will affect the populations of other living organisms in the same habitat. Study again the same food chain below. Assume that there are only three populations in this habitat. Leaves If the hunters catch the lions in this habitat, what will happen to the other populations? The possibilities would be: • The number of lions decreases. • The population of deer increases because reproduction happens and fewer lions prey on them. • The population of plants decreases as a large number of deer depends on them as food. If this situation continues, what will happen to the deer? The deer will eventually die of hunger as the amount of plants is too little for them. Decomposers There is another group of organisms that plays an important role at the end of each food chain. They are decomposers—bacteria and fungi. They break down dead animals and plants into simpler substances. These substances are released into the soil as nutrients to be used by plants for growth. They are important to prevent the Earth from being covered by dead, waste materials. Bacteria that is found on a dead body will decompose it into simpler substances. Fungi grow on a dead tree log. We should protect animals by not hunting them illegally. All living organisms play their roles to keep the number of populations in a habitat balanced. Relationship among Chapter 2 Living Things 37
Fill in the blanks. 1. An individual animal, plant or bacterium is a living . 2. A is the natural environment where animals and plants live. 3. A group of animals or plants of the same kind that lives and reproduces in the same habitat is known as a . 4. Different populations of organisms that live together form a . 5. The living organisms are interdependent and interact with non-living components in their physical environment to form the . 6. We can find populations of bees and flowers in the community. 7. In the community, the frogs lay eggs under the leaves of the water lilies. 8. The food chain begins with a which is the plant that makes food using sunlight. 9. Animals and humans that depend on plants and other animals for food are known as . 10. A food shows how a living organism becomes the food for another. 11. A food shows the relationship between two or more food chains in an ecosystem. 12. In a food chain or a food web, the original source of all the energy is the . 13. The role of at the end of each food chain is to break down dead animals and plants into simpler substances. 14. All the living organisms play their roles in a food chain to maintain a ecosystem. balanced habitat web consumers producer garden community Sun chain organism population pond ecosystem decomposers Let’s Scan 38 Hands-on Science Primary 6
Map It Out Relationships among living things Made up of different populations of animals and plants that live in the same habitat A group of organisms of the same kind that lives and reproduces in the same habitat. Population It is a community of interacting organisms and their physical environment. The organisms interact with each other and also with non-living things. Ecosystem It is a living thing such as an animal, plant or bacterium. Organism Community Online QuickQuiz Explain It Organisms, populations and communities • An organism is a living thing. • A group of living things of the same kind forms a population in a habitat. • Many populations form a community. • The populations live together, depend on each other and interact with non-living components to form the ecosystem. Communities at different habitats Roles of living organisms in feeding relationships Different populations that live in different communities such as the garden, pond, seashore, tree and mangrove swamps are interdependent for survival. • The feeding relationships between producers and consumers can be represented using a food chain or a food web. • The energy in the food webs is transferred from the Sun, to the producers, followed by consumers and ends with decomposers. Relationship among Chapter 2 Living Things 39
Chapter 3 What do I know about human impact on the environment? 1. 2. 3. What do I want to know about human impact on the environment? 1. Identify human activities that affect the natural balance. 2. Describe how human activities impact the environment. 3. Recognize the importance of conserving the environment to sustain the natural balance. Human Impact on the Environment The Sumatran rhino is one of the top ten Indonesian endangered species. There are about 100 of them left in Sumatra and Kalimantan. Human activities such as deforestation have destroyed their habitat, and illegal hunting is driving them to extinction. What will happen to these animals if we keep cutting down the trees for development?
Impact of Human Activities on the Environment 3.1 Human activities impact the physical environment in many ways such as the depletion of natural resources, pollution and global warming. Human activities have disturbed the natural balance in many ways. Depletion of Natural Resources Mining is the extraction of minerals or other materials from the Earth. Once they are removed from the ground, they cannot be replaced. Humans get the extracted minerals to make objects used for clothing, housing and other things. A pump jack that is used to drill crude oil from the ground in the petroleum industry produces loud noises. Loud noises and vehicle traffic from drilling operations can disrupt wildlife habitats. Coal mining Overfishing will cause the depletion of certain types of fish in the sea as the quantity of the fish caught is greater than the breeding population. As a result of prolonged overfishing, some types of fish will decrease. People who rely on fish as a key source of protein will face a food crisis. Depletion of natural resources happens when we consume resources faster than we replace them. Why does this happen? As the world population increases, the demand for natural resources becomes greater to support the population. Fossil fuels such as coal, natural gas and petroleum are natural resources. Coal and natural gas are used to produce electricity for the use of factories or industrial processes while petroleum is the energy source for transportation. They are non-renewable resources that cannot be replaced once they are consumed and depleted. Overfishing can also have an impact on marine communities. When too many fish are taken out of the sea, it disturbs the food chains and many other types of marine life are lost. Human Impact on Chapter 3 the Environment 41
Pollution Pollution is the process that makes our environment dirty and unhealthy. The three major types of pollution as a result of human activities are air pollution, water pollution and land pollution. Air Pollution Air pollution occurs when harmful chemicals, gases or substances are released into the air. This polluted air will bring harmful effects to humans or other living things when inhaled. The process of clearing the forests through cutting down or burning trees for other purposes is called deforestation. Burning trees can produce huge amounts of ash, dust and smoke which form a haze that can cause breathing difficulties. Deforestation Burning of fossil fuels Burning of fossil fuels that include coal, oil and natural gas can release all kinds of gases or fumes into the air, causing smog. All the harmful fumes released can dissolve in rainwater to form acid rain that can kill living things and corrode metals. Use of chlorofluorocarbons (CFCs) Fumes from spray cans, such as aerosol sprays, release CFCs into the air that are harmful to the ozone layer. The ozone layer is a layer that protects the Earth from most of the ultraviolet (UV) rays from the Sun. If this layer gets thinner, we will be exposed to excessive UV rays which can harm our eyes and cause skin cancer. Human Activities that Cause Air Pollution Burning fuels in factories and power plants produce harmful fumes that can cause sore eyes and lung cancer. The exhaust fumes produced from vehicles also contain harmful gases that can ruin our health if we are exposed to them in the long run. 42 Hands-on Science Primary 6
When fertilizers and pesticides from farming activities are released into water bodies, they cause harmful effects to the organisms living in it. Human Activities that Cause Water Pollution Water Pollution Water pollution occurs when harmful chemicals, waste or other particles are released into the rivers, lakes and oceans. Water pollution can disrupt the water cycle and affect organisms that consume the contaminated water. Improper disposal of waste The unwanted waste dumped into water causes pollution when the harmful substances in it get into the water. Release of harmful chemicals Oil spills Petroleum is a form of chemical that usually contaminates water through oil spills from ships. Oil spills can spread for miles to cause the death of aquatic life and stick to the feathers of seabirds, causing them to lose the ability to fly. Dumping of toxic waste and chemicals from factories pollutes the water and poisons aquatic life. Polluted water with white foam and oil slicks on the sea. Discuss in groups to share your ideas on the following questions. Present the outcomes through role play or a PowerPoint slide show. • What are the other human activities that cause pollution in your country? • What are the effects of each of the activities on the environment? • What can you do to reduce pollution? Let’s Find Out! Human Impact on Chapter 3 the Environment 43
Land Pollution Land pollution occurs when harmful chemicals and rubbish are released into the soil. It damages the land and reduces its availability for residential, agricultural and other purposes. Human Activities that Cause Land Pollution Excessive use of chemicals Excessive use of fertilizers and pesticides in farming contaminates the soil, water and other vegetation. It also kills insects or other organisms living in the soil. Mining Mining activities produce large holes in the ground that can lead to soil erosion when the rain washes the loosened topsoil. It can also release toxic chemicals into the air and soil. Improper disposal of garbage and waste Garbage from littering or the waste from factories might consist of toxic substances that cannot be broken down by bacteria and fungi. These substances will remain in the soil for a long time if they are not disposed of properly. They can cause the death of animals and plants, disrupt the food chain and affect the environment. A landfill is a place where disposed waste material is buried. Landfills are the most common and oldest form of waste treatment. They are also used for waste management such as for temporary storage, sorting, treating or recycling of waste material. Improper disposal of garbage and waste by people at the beach. 44 Hands-on Science Primary 6
Global Warming The heat and light energy from the Sun enables living things on Earth to carry out their life processes. When heat reaches the Earth, some is reflected back to space and some is trapped on the Earth due to the presence of carbon dioxide in the air. Warming effect Carbon dioxide in the atmosphere Some heat trapped on Earth Heat reaches the surface of Earth Heat that is reflected back to space Human activities, such as deforestation and burning of fossil fuels will cause the release of carbon dioxide into the atmosphere. When more and more carbon dioxide gets into the atmosphere, the Earth starts to grow warmer because more heat is trapped. Thus, global warming begins when there is a gradual increase in world temperatures caused by more carbon dioxide collecting in the air. Volcanic eruptions can change the temperature of Earth for a short period of time because a large amount of carbon dioxide is emitted into the atmosphere during the eruptions. At the same time, large amounts of ash released into the atmosphere also cause air pollution. Human Impact on Chapter 3 the Environment 45