Section A: Attempt all questions. (55 marks)
For all multiple choice questions, circle a letter
corresponding to the correct answer.
1) Why are flowering plants important to the environment? (1
mark)
a) They provide oxygen.
b) They prevent erosion.
c) They help in the production of food and oxygen.
d) They absorb carbon dioxide only.
Answer
c) They help in the
production of food and oxygen.
Explanation: Flowering plants undergo photosynthesis,
absorbing $CO_2$ and releasing oxygen, while acting as the primary producers
(food source) for the food web.
2) Which of the following is the primary characteristic that
distinguishes the phylum Arthropoda from other animal phyla? (1 mark)
a) Radial symmetry.
b) Exoskeleton made of chitin.
c) Presence of a backbone.
d) Bilateral symmetry.
Answer
b) Exoskeleton made of
chitin.
Explanation: While arthropods have bilateral
symmetry, their defining, unique evolutionary feature compared to other animal
phyla is their hard chitinous exoskeleton and jointed appendages.
3) The total magnification of a microscope is calculated by
multiplying the magnification of the ocular lens by the magnification of the
objective lens. If the ocular lens magnifies 10x and the objective lens
magnifies 40x, what is the total magnification? (1 mark)
a) 4x
b) 4000x
c) 400x d) 40x
Answer:
c) 400x
Explanation: Total magnification = Ocular lens
magnification (10x) x Objective lens magnification 40x = 400x.
4) Which of the following organelles is responsible for
protein synthesis in both plant and animal cells? (1 mark)
a) Golgi apparatus.
b) Endoplasmic reticulum.
c) Ribosomes.
d) Lysosomes.
c) Ribosomes.
Explanation: Ribosomes are the cellular machines
responsible for translating mRNA into proteins in all living cells.
5) Match the nutrient in column A with its primary function in column B. (5 marks)
|
A:
Nutrient |
B:
Function |
|
i)
Carbohydrates |
a) Provide
energy for the body. |
|
ii) Proteins |
b) Support
immune function and cell repair. |
|
iii)Fats |
c) Aid in the
formation of bones, teeth, and blood. |
|
iv)Vitamins |
d) Provide
energy and help in the absorption of fat-soluble vitamins. |
|
v)Minerals |
e) Facilitate
various biochemical processes in the body. |
Answer:
i) ------ > a)
ii) ------ > b)
iii)------ >d)
iv)------ > e)
v)------ >c)
6) State whether each of the following statements is True or
False
a) In passive transport, molecules move from an area of low
concentration to an area of high concentration. (1 mark)
a) False.
Explanation: Passive transport moves molecules from
an area of high concentration to low concentration (down the
gradient).
b) Osmosis is a type of facilitated diffusion that requires
a carrier protein. (1 mark)
b) False.
Explanation: Osmosis is specifically the diffusion of
water molecules across a selectively permeable membrane, not a facilitated
diffusion requiring a carrier protein.
c) Active transport moves molecules against their
concentration gradient using energy, whereas passive transport moves molecules
down their concentration gradient without energy. (1 mark)
c) True.
Explanation: This perfectly defines the difference
between active (uses ATP, moves against gradient) and passive transport.
7) Circle the letter corresponding to the best answer: Which
of the following statements best describes the role of enzymes in biochemical
reactions? (1 mark)
a) Enzymes are consumed in chemical reactions and cannot be
reused.
b) Enzymes act as catalysts, speeding up the rate of
biochemical reactions without being consumed.
c) Enzymes change the direction of chemical reactions.
d) Enzymes increase the energy required for reactions to
occur.
b) Enzymes act as catalysts,
speeding up the rate of biochemical reactions without being consumed.
8) Match each condition in column A with its effect on the
rate of photosynthesis in column B. (5 marks)
|
A: Condition |
B: Effect on
the rate of photosynthesis |
|
i) Increased
light intensity |
a) Increases
the rate of photosynthesis until the saturation point is reached |
|
ii) Increased
carbon dioxide concentration |
b) Can
decrease the rate if too extreme |
|
iii)
Increased temperature |
c) Increases
the rate of photosynthesis, up to a limit |
|
iv) Decreased
light intensity |
d) Decreases
the rate of photosynthesis |
|
v) Reduced
water availability |
e) Reduces
the rate of photosynthesis significantly |
Answer:
i)------ > a)
ii) ------ > c)
iii) ------ > b)
iv) ------ > d)
v)------ > e)
9) Match each plant structure in column A with its primary
function in the transport system in column B. (5 marks)
|
A: Structure |
B: Function |
|
i) Xylem |
a) Transport
of water and minerals from the roots to other parts of the plant. |
|
ii) Phloem |
b) Transport
of organic food (mainly sugars) from leaves to other parts. |
|
iii) Root
Hair |
c) Absorb
water and minerals from the soil. |
|
iv) Stomata |
d) Facilitate
gas exchange for photosynthesis. |
|
v) Leaves |
e) Perform
photosynthesis to produce food for the plant. |
i)------ > a)
ii)------ > b)
iii)------ > c)
iv)------ > d)
v)------ > e)
10) State whether each of the following statements is True
or False.
a) In meiosis, two rounds of division (meiosis I and meiosis
II) result in the production of four genetically diverse haploid cells. (1
mark)
True.
Explanation: Meiosis I and II result in four
non-identical haploid gametes.
b) Mitosis is responsible for producing genetically
identical cells, whereas meiosis produces cells with half the chromosome number
of the original cell. (1 mark)
True.
c) In meiosis, crossing over occurs during metaphase I,
leading to genetic recombination. (1 mark)
False.
Explanation: Crossing over occurs during Prophase
I, not Metaphase I.
11) Match each characteristic of heterotrophic nutrition in
column A with its correct description in column B: (4 marks)
|
A:
Characteristic |
B:
Description |
|
i) Ingestion |
a) The
process of breaking down food into simpler molecules. |
|
ii) Digestion |
b) The
process of absorbing nutrients into the bloodstream. |
|
iii)
Absorption |
c) The intake
of food into the organism’s body. |
|
iv) Egestion |
d) The
removal of undigested food from the body. |
Answer
i)------ > c)
ii) ------ > a)
iii)------ > b)
iv)------ > d)
12) What is the primary function of the human circulatory
system? 1 Mark
a) To circulate air throughout the body.
b) To transport nutrients, oxygen, and waste products.
c) To transport hormones and enzymes.
d) To protect the body from pathogens.
Answer
b) To transport nutrients,
oxygen, and waste products.
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13) In the absence of oxygen, what process does the body
rely on to produce energy during intense exercise? (1 mark)
a) Aerobic respiration.
b) Lactic acid fermentation.
c) Alcoholic fermentation.
d) Glycolysis.
Answer
b) Lactic acid fermentation.
14) Which of the following is an example of how the skin
helps maintain body temperature during excessive heat? (1 mark)
a) Vasodilation and sweating.
b) Vasoconstriction and shivering.
c) Increased blood flow to the internal organs.
d) Decreased sweating and increased hair growth.
Answer
a) Vasodilation and sweating.
15) In the human eye, which part is primarily responsible
for detecting light and converting it into nerve impulses? (1 mark)
a) Retina
b) Lens
c) Cornea
d) Pupil
Answer
a) Retina
16) Match the reproductive organs in column A with their
functions in column B. (4 marks)
|
A:
Reproductive Organ |
B: Function |
|
i) Testis |
A) Production
of eggs |
|
ii) Ovary |
B) Production
of sperm |
|
iii) Uterus |
C) Site of
fertilization |
|
iv) Fallopian
tube |
D) Site where
the embryo develops |
Answer
i) ----- > B)
ii)------ > A)
iii)------ > D)
iv) ------ > C)
17) Which of the following best describes a virus? (1 mark)
a) A microorganism that can reproduce independently.
b) A non-living particle that needs a host cell to
replicate.
c) A type of bacteria that causes infections.
d) A protozoan parasite that infects humans.
Answer
b) A non-living particle that
needs a host cell to replicate.
18) State whether each of the following statements is True
or False:
a) Using condoms correctly during sexual intercourse can
reduce the risk of contracting HIV and other STIs. (1 mark)
True.
b) HIV can be transmitted through casual contact, such as
shaking hands or hugging (1 mark)
False.
c) Limiting the number of sexual partners can reduce
the risk of contracting STIs and HIV.
True.
d) Taking PrEP (Pre-exposure Prophylaxis) can help reduce
the risk of acquiring HIV in high-risk individuals. (1 mark)
True.
e) Sharing needles for drug use is a common way that HIV can
be transmitted. (1 mark)
True.
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19) A family who regularly attends community health
education programs is more likely to: (1 mark)
a) Neglect healthy
habits in favor of traditional practices.
b) Be more aware of health risks and preventive measures.
c) Avoid healthcare professionals due to distrust.
d) Ignore healthcare and physical exercise.
Correct
b) Be more aware of health
risks and preventive measures.
20) When deciding whether to have a sexual relationship,
which of the following should a young adult consider to make an informed and
responsible decision? (1 mark)
a) The level of sexual experience each partner has.
b) The availability of birth control methods.
c) The long-term emotional and physical consequences of the
relationship.
d) Whether the relationship is romantic or based purely on
physical attraction.
Correct
c) The long-term emotional
and physical consequences of the relationship.
21) How does the water cycle contribute to sustaining
ecosystems? (1 mark)
a) It increases the salinity of water bodies.
b) It ensures water is continuously available to plants,
animals, and humans.
c) It stops the evaporation of water.
d) It prevents the contamination of water sources.
Answer
b) It ensures water is
continuously available to plants, animals, and humans.
22) How does migration affect the population growth rate of
a species in a given area? (1 mark)
a) Migration out of an area typically increases the local
population growth rate.
b) Migration into an area increases the local population
growth rate by introducing new individuals.
c) Migration has no effect on population growth rates.
d) Migration always results in a decrease in population
growth.
Answer
b) Migration into an area
increases the local population growth rate by introducing new individuals.
23) Which of the following human activities is most directly
linked to habitat destruction? (1 mark)
a) Overfishing.
b) Recycling.
c) Deforestation.
d) Sustainable agriculture.
Correct
c) Deforestation.
24) In which type of reproduction do offspring inherit
traits from only one parent? (1 mark)
a) Asexual reproduction
b) Sexual reproduction
c) Both asexual and sexual reproduction
d) Budding
Answer
a) Asexual reproduction
25) State whether each of the following statements is True
or False:
a) Pollination is the process of fertilization in flowering
plants. (1 mark)
False.
b) The pistil is the female reproductive part of a flower.
(1 mark)
True.
c) The sperm cell in pollen fuses with the egg cell in the
ovule during fertilization. (1 mark)
True.
d) Fertilization results in the formation of a zygote, which
later develops into a seed. (1 mark)
True.
e) In sexual reproduction, all offspring of flowering plants
are genetically identical. (1 mark)
False.
Section B: Essay Questions (30 marks - 10 marks each)
26) How does predation influence the population of the prey
species, and why is this not the case for scavengers? (10 marks)
Predation: Predators directly regulate prey
populations by hunting and killing living organisms for food. This creates a
direct downward pressure on the prey numbers, often resulting in a cyclic
relationship (as prey increases, predators increase, which then drives prey
down).
Scavengers: Scavengers feed on the remains of animals
that are already dead. Because they do not hunt or kill live animals,
they do not directly remove living reproducing members from the prey
population, meaning they have little to no direct influence on the population
growth rate of that species.
27) Evaluate the role of ovulation timing in the likelihood
of fertilization and the factors that contribute to this process. (10 marks)
Role of Timing: Fertilization can only occur if live
sperm meet a viable egg. Ovulation is the release of a mature egg, which only
survives for 12-24 hours. Because sperm can survive in the female reproductive
tract for 3-5 days, the "fertile window" is highly restricted to the
few days just before ovulation and the day of ovulation itself.
Contributing Factors: The timing of ovulation is
primarily controlled by hormones (a surge in Luteinizing Hormone [LH] triggers
ovulation, regulated by Estrogen and Progesterone). Other factors influencing
timing include the individual's menstrual cycle length, stress levels,
nutrition, and overall health, which can cause ovulation to occur earlier or
later than expected.
28) Osmosis is an important process in plants. Justify. (10
marks)
Water Absorption: It is the primary mechanism by
which plant root hair cells absorb water from the soil (moving from higher
water potential in the soil to lower potential in the root cells).
Structural Support (Turgidity): Osmosis allows plant
cells to take in water and become turgid. This turgor pressure pushes against
the cell wall, keeping non-woody (herbaceous) plants upright and preventing
them from wilting.
Stomatal Regulation: The opening and closing of
stomata for gas exchange is controlled by the osmotic movement of water in and
out of the guard cells.
29) A homozygous sweet pea with white flowers was crossed
with a homozygous sweet pea with red flowers. All of the offspring had red
flowers.
a) State which allele of this gene is dominant. (1 mark)
Dominant allele: The Red allele is dominant. (We know
this because crossing a homozygous white with a homozygous red produced only
red offspring).
b) Two heterozygous sweet pea plants with red flowers were
crossed as shown below.
Draw a Punnet square to show the genotypes that are produced in this cross.
Punnett Square for Rr x Rr:
|
Gametes |
R |
r |
|
R |
RR (Red) |
Rr (Red) |
|
r |
Rr (Red) |
rr (White) |
c) State the phenotypic ratio produced in this cross.
Phenotypic ratio: 3 Red flowers : 1 White flower (or
3:1).
Section C: Compulsory Practical Application (15 marks)
30) Assume you are provided with the following materials and
tools: DCIP, orange, test tubes, droppers, syringes, beakers, knife.
Food Test (DCPIP / Vitamin C)
a) Use the materials provided to prepare an extract of food
sample. 6 Marks
Using the provided knife, carefully cut the orange
in half.
Squeeze the juice from the orange halves into one of the beakers.
Ensure the collected orange juice extract is relatively
clear of large pulp or seeds to not obstruct the chemical test later.
b) Test the food component present in that fruit (procedure,
result and conclusion (9 marks)
Procedure:
1. Using a clean syringe, measure a small, fixed
volume (e.g., 2 cm³) of the blue DCPIP solution and place it into a test
tube.
2. Using a dropper, take some of the prepared orange
juice extract.
3. Add the orange juice extract drop by drop into the test
tube containing the DCPIP.
4. Gently shake or swirl the test tube after adding each
drop. Continue until a color change is observed.
Result: The blue color of the DCPIP solution
gradually disappears (decolorizes) upon adding the orange juice, eventually
turning clear or taking on the slight natural tint of the juice.
Conclusion: The decolorization of the DCPIP solution
confirms the presence of Vitamin C (Ascorbic Acid) in the orange
extract.
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