Revision DB024 PSPM set ( K M Klntn )

Anwer all questions given in space provided

1 (a) FIGURE 1 below shows the terrestrial ecosystem of a tropical rainforest.















O




Forest floor Shrubs

FIGURE 1

i. Define ecosystem? [1 mark]

The functional unit of nature including both living organisms and their
non living environment that interacting and influencing each other.

ii. Identify strata M, N and O. [3 marks]

M : Emergent layer
N : Canopy layer
O : Understory layer

iii. Describe the characteristic of forest floor with an example of animal found in [3 marks]
this area.
- Dark, hot and damp due to little penetration of sunlight
- The floor covered with decomposing vegetation and organism that
breakdown into usable nutrients
- Example of animals: centipedes // ant // earthworm // tapirs // insects //
cockroaches // beetle // scorpions

iv State the abiotic and abiotic components in the tropical rainforest. [2 marks]
.
- Biotic component: Tree / Animal
- Abiotic component: Atmosphere // hydrosphere // litosphere

v. What is the role of tropical rainforest in the carbon cycle. [2 marks]
- Plant take in / fix carbon dioxide from the atmosphere during
photosynthesis.
- Decomposition of plant and animal returns the carbon into the reservoir
pool.




BLUE 3 DB024 SESSION 2021/2022

2 (a) Figure 2A shows the types and sources of variation.

Variation





Type Sources



A Discontinous Genetic B


FIGURE 2A
i Define variation [1 mark]
Is the differences in the morphology, physiology and behaviour of
different individuals from the similar species.

ii Name A and B [2 marks]
A: Continous (variation)
B: Environmental

iii Give TWO differences between genetic variation and B. [2 marks]
Genetic variation B / Environmental
Affects genetic material Affects only the phenotype
(phenotype and genotype)
Contributors: Contributors:
- gene mutation - Food/nutrients
- chromosome mutation - Water
- crossing over - Soil
- Climate
Play important role in evolutionn Not of much importance in
(raw material in natural selection) evolution.
Can be passed on from generation Cannot be passed on.
to generation
Any TWO






















BLUE 3 DB024 SESSION 2021/2022

(b) FIGURE 2B shows a type of speciation within beetle population.




















FIGURE 2B
i. What is meant by speciation? [1 mark]
Evolutionary process by which one or more new biological species arise
from previously existing species.

ii. State TWO factors that leads to speciation. [2 marks]
- Reproductive isolation
- Genetic drift
- Hybridization
- Adaptive radiation
Any TWO

iii. Two closely related fish live in the same lake but one feeds along the
shoreline and the other is a bottom feeder in deep water. It is found that both of
the related fish are unlikely to interbreed.

According to the statement above, name the mechanism/barrier that prevent
them from interbreed. [1 mark]
Prezygotic barrier






























BLUE 3 DB024 SESSION 2021/2022

3 (a) FIGURE 3 shows two mechanisms of enzyme inhibition.



















FIGURE 3
i. Define inhibitors. [1 mark]

Molecules that prevent catalyzing reactions when they are bound to
the enzymes.
ii. State the type of the inhibitor X and Y . [2 marks]
X: Competitive inhibitor
Y: Non-competitive inhibitor

iii. Explain what happens to the rate of reaction in the presence of the inhibitor X. [2 marks]
- The rate of reactions reduced/ slow down/ decrease.
- Because the inhibitor prevents the substrate molecule from occupying
/ binding to the active site of enzyme.

iv Briefly explain how the effect of the inhibitor X can be overcome. [2 mark]
. - By increase the concentration of substrate.
- Because chances of substrate binding with active site is increased.


(b) Why quick-freezing food is one way of preserving food for long period? [2 marks]

- Low / cold temperature deactivates / slows down digestive enzymes of
microbes
- Some enzymes lose their function when frozen making food
impossible to decompose by microbes












BLUE 3 DB024 SESSION 2021/2022

4 FIGURE 4 shows the Electron Transport Chain and ATP synthase.





















FIGURE 4

(a) State the importance of oxygen as a final electron acceptor in this system? [1 mark]
- To form water

(b) Describe what happen when complex III accepting electron. [2 mark]
- Complex III will be reduced
- Complex III pump the H+ from matrix to intermembrane space

(c) Explain briefly oxidative-phosphorylation that occurs to generate ATP. [4 marks]
• Electrons from the electron carrier will go through the series of redox
reaction at protein complex.
• H+ will pump out from the matrix of mitochondria into the
intermembrane space and
• Create the electrochemical gradient/Proton motive force.
• H+ diffuse back into the matrix of mitochondria through ATP synthase
from intermembrane space.
• ATP will form through phosphorylation/ ADP is phosphorylated to form
ATP
(d) What will happen to the system in FIGURE 4 if inhibitor is added to complex [2 marks]
IV.
- The flow of electrons from Cytochrome c Oxidase/Complex IV to
oxygen will stop/halted.
- Inhibit Cytochrome c Oxidase from pump H+ from the matrix to
intermembrane space and function efficiently.













BLUE 3 DB024 SESSION 2021/2022

5 FIGURE 5 below shows stage during photosynthesis.














FIGURE 5
(a) Identify A and B. [2 marks]
A: Photon / light energy
B: Water / H2O

(b) In terms of electron deficiency, give ONE difference between reaction centre [1 mark]
P680 and P700.
Electron deficiency in P680 is replaced by electrons from photolysis of
water, while in P700, electron deficiency is replaced by electrons from
P680

(c) Name the type of reaction to synthesis ATP that occur in FIGURE 5 above [1 mark]
Non-cyclic photophosphorylation.

(d) ATP and NADPH are product of process in FIGURE 5. State the role of ATP [2 marks]
and NADPH during Calvin cycle.
ATP: energy source // phosphorylate 3-phosphoglycerate to become 1,3-
bisphosphoglycerate.
NADPH:reducing agent // reduce 1,3 – bisphosphoglycerate to become
glyceraldehyde- 3-phosphate / G3P

6 Transportation of CO2 from tissues to the lung mostly by formation of [6 marks]
-
bicarbonate ion, HCO3 . State where it form and explain its formation.

- bicarbonate ion, HCO3 form in red blood cell / erythrocytes 1
-
- as CO2 enter red blood cell / erythrocytes, CO2 react with water forming 1
carbonic acid, H2CO3
- catalysed by carbonic anhydrase 1
- Carbonic acid, H2CO3 dissociate 1
+
-
- forming hydrogen ion, H and bicarbonate ion, HCO3 1
- HCO3 diffuse out into blood plasma and combine with sodium ion to 1
-
form sodium bicarbonate and transported to the lung.






BLUE 3 DB024 SESSION 2021/2022

7 FIGURE 6 shows the transport pathways of water in a plant.

















FIGURE 6
(a) Identify pathway 1 in FIGURE 6 and how water is transported [2 marks]
- Apoplast pathway
- Water molecules diffuse / move along cell walls and extracellular spaces
of adjacent cells

(b) Name the structure in tissue F that hinders water movement in pathway 1. [1 mark]
Casparian strip

(c) Suggest how would the plant overcome the problem in (b)? [2 marks]
- Water molecules move / diffuse out of the cell wall into cytoplasm
- and transported through symplast pathway

(d) Identify the upward force that helps to push water in xylem vessel of H to a [1 mark]
certain height.

Root pressure


























BLUE 3 DB024 SESSION 2021/2022

8 FIGURE 7 shows the structure of nephron.






























FIGURE 7

(a) Give THREE factors that increase the efficiency of the process occurring in H. [3 marks]
• High hydrostatic pressure // high blood pressure // high resistance to
blood flow // afferent diameter is larger than efferent // blood flow is
slow
• High surface area // coiled blood capillaries
• High permeability
• More porous // high number of pores // podocytes present
(ANY 3)


(b) Give an example of a substance that is secreted into tubule M [1 mark]
+
+
+
K // H // urea // drug // NH

(c) State the process that occurs in N. [1 mark]
Reabsorption of NaCl / water / urea

(d) Why does a desert rat have longer tubules K and L? [1 mark]
To avoid excessive water loss // more water can be reabsorb // to
increase surface area for reabsorption.











BLUE 3 DB024 SESSION 2021/2022

9 FIGURE 8 shows the action of a hormone on its target cell.


















FIGURE 8
(a) State ONE characteristic of the hormone in FIGURE 8 which enable it to enter [1 mark]
the target cell.
Lipid soluble/hydrophobic

(b) What type of hormone is shown in figure above? [1 mark]
Steroid hormone

(c) Name structure A, B and C. [3 marks]
A : hormone receptor/ receptor (in cytoplasm)
B : hormone receptor/ receptor (in nucleus)
C : hormone-receptor complex

(d) Briefly describe the action of the hormone in figure above. [4 marks]
• Hormone passes through the plasma membrane of the target
cell.
• Hormone binds to the receptor in cytoplasm or nucleus
forming the hormone-receptor complex.
• Hormone-receptor complex binds to a specific site on DNA

• causes transcription of mRNA, which is then translated into
proteins at cytoplasm.











BLUE 3 DB024 SESSION 2021/2022

10 (a) FIGURE 9A shows the structure of an antibody molecule












FIGURE 9A

i Identify P [1 mark]
Antigen binding site

ii Between Q and S, which will determine the class of antibody? [1 mark]
S

iii Name the cell that secretes antibodies. [1 mark]
Plasma cell / Plasma B cell

iv Why does antibody’s action is specific for a particular antigen? [1 mark]
The conformation/ shape of the antigen-binding sites of the antibody is
specific to a particular antigen.

(b) FIGURE 9B represents the immunological memory in human body.









FIGURE 9B
i Define primary immune response [1 mark]
Immune response that occur during the first exposure to an antigen.

ii Peak A and B is a response of human immune system against the same [4 marks]
antigen. Why peak B is higher than peak A?
- Peak Y is a secondary immune response.
- The memory B cells recognize the same antigen and
- rapidly differentiate into plasma cell to secrete antibody
- High concentration of antibody is produced in shorter time






BLUE 3 DB024 SESSION 2021/2022