WASSCE 2015 BIOLOGY PAPER QUESTIONS AND ANSWERS.

QUESTION 01

(a)Explain briefly sexual reproduction in Rhizopus.

Answer: Sexual reproduction in Rhizopus – By conjugation.

It is usually between two strains of hyphae
Known as + and – plus and minus/ opposite mating types
The hyphae come in contact
And produce small projections of their walls
Which develops into Progamentangia with several nuclei
The two Progamentangia enlarge
Each progametangium develops a cross wall to divide into two parts: the gametangium and the suspensor
Subsequently, the wall dissolves/breaks, and their contents/nuclei fuse to form a zygote
The zygote develops a thick wall to form a resistant zygospore
The zygospore germinates during favourable/damp/wet conditions
Into hyphae which bear

(b) A student suddenly stepped on a big snake, and he cried for help and ran away.

(i) Name the hormone produced in the body for the reaction.

Answer:

Adrenalin /Adrenaline

(ii) In which part of the human body is the hormone named in (b) (i) produced?

Answer:

Adrenal gland/Medulla.

(c) State five changes that must have taken place as a result of the hormone named in (b) (i).

Answer: Changes that must have taken place as a result of the hormone

Increase in heartbeat
Increase in rate of respiration
Arterioles of the skin and alimentary canal constrict
Dilation of blood vessels that causes more blood to flow to the muscles/heart/lungs
Increase in muscular tone/voluntary muscles become tensed
Glycogen is converted to glucose/increase in blood sugar level
To produce more
Dilation of the pupils of the
Momentary freight/fear/anxiety/heavy breathing.
The spleen releases more Red Blood Cells from its reserve.
Increase in blood pressure.

(d) (i) In tabular form, state three differences between excretion in flowering plants and excretion in humans.

Differences between excretion in flowering plants and excretion in humans.

Flowering plants	Humans
No definite excretory organs	Definite excretory organs /presence of kidney/liver/skin
Waste products include tannins/ resins/ alkaloids/ gums, etc.	Waste products include urine/urea/sweat/ salts, etc.
Excretory products are produced in small quantities	Excretory products are produced in large quantities
Excretory products are released at a slower rate	Excretory products are released at a faster rate
Most excretory products, tannins/ resins/ alkaloids/ gums are stored	Most excretory products are completely removed
Some excretory products/carbon dioxide/oxygen/water vapour can be reused	Some excretory products/urea/uric acid, cannot be reused
Excretory products are derived from simple organic molecules	Excretory products are derived from complex organic molecules.

(ii) List two organelles found in a plant cell that are responsible for the excretion of metabolic wastes.

Organelles in plant cells responsible for the excretion of metabolic wastes.

Mitochondrion/mitochondria;
chloroplast/ chloroplasts.

Question 02

(a) Explain how the leaf of a flowering plant is adapted for photosynthesis.

Adaptation of the leaf for photosynthesis

Broad/flat leaf lamella, exposing a large surface area for maximum absorption of light
Palisade mesophyll cells contain a lot of chloroplast chlorophyll for maximum absorption of light
Position of leaf to stem; for optimum reception of light rays/sunlight
Thin lamella allows light penetration into the leaf tissue of the mesophyll
Palisade cells are at right angle/perpendicular to the upper epidermis/chloroplasts are arranged in the periphery of the cells; all for easy activation of the chloroplasts for photosynthesis
Large vacuoles of the palisade cells store photosynthetic products
Large intracellular air spaces in the spongy mesophyll allow oxygen/carbon dioxide to diffuse in/out of the chlorophyllus cells/for gaseous exchange
The epidermal cells have thin cell walls, for easy penetration of sunlight to the mesophyll
Guard cells have chloroplasts for the absorption of sunlight
The bean-shaped structure of the guard cell allows for gaseous exchange
The stomata open easily when they become turgid for the diffusion of gases/carbon dioxide/oxygen
Xylem conducts water into the leaves for photosynthesis
Phloem transports manufactured food to other parts of the

(b) Describe briefly the mode of feeding in the tapeworm.

The mode of feeding of the tapeworm.

Parasitic mode of feeding;
Lives in the gut of man/pigs;
It has hooks/suckers; which enable it attach itself to the lining of the intestine of the host;
Has a flattened tape-like/ribbon-like body; provides a large surface area for easy absorption of digested food.
Has no alimentary/digestive system.

(c) Name one mineral element each needed for the proper functioning of :

Bones:

Calcium,
phosphorus,
fluorine

Red blood cells:

Iron,
copper

Thyroid gland:

Iodine

(d) (i) State three benefits of including roughages in the diet of humans.

Benefits of including roughages in the diet of humans :

Stimulates bowel movement/peristalsis
Reduces blood cholesterol/bowel cancer/gallstones/appendicitis/obesity/diabetes mellitus
They do not contribute to weight gain/high blood sugar
It releases glucose slowly
It prevents constipation.

(ii) State three reasons why proteins are important to humans.

Importance of proteins to humans.

For the repair of damaged tissues, replacement of worn-out tissues
For bodybuilding
For growth
For the supply of the necessary amino acids
For the formation of hormones/enzymes/antibodies/ forming fibrinogen necessary for blood clotting.

QUESTION 3

(a)(i) What is sewage?

Sewage:

Waste matter/faeces, urine, waste water from animals/industrial/domestic sources, that is dissolved/ suspended in water.

(ii) State five effects of releasing untreated sewage into a stagnant water body.

Effects of releasing untreated sewage into a stagnant water body.

Spread of water-borne diseases/correctly named diseases/microbes/pathogens
May be toxic/poisonous to aquatic life/organisms
Makes water unfit for consumption/use
Increased decomposition
Increased concentration of nutrients
Rapid growth of algae/aquatic plants/algal bloom/eutrophication
Depletion of oxygen
Suffocation/death of aquatic animals
Generates offensive odour/air pollution
Nutrient/nitrate/phosphate enrichment/accumulation in a water body, as a result of breakdown by

(b) Explain surface terracing as a soil conservation method.

Surface terracing as a soil conservation method :

A method of controlling erosion on a gentle/steep slope of a hill;
Flat horizontal areas are constructed on which crops are cultivated,
Following the contour, steps/walls are built along the contours;
Ploughing is also done along the contours;
This reduces the speed of water running down the slopes.

(c) Explain the term adaptation.

Adaptation :

Is the possession of the characteristic/trait/behaviour/structure/feature that evolved over a period, enabling an organism to survive and reproduce, in response to changes in the environment/habitat.

(d) Explain two ways in which the following organisms adapt to their habitats:

Adaptation of;

Hydrophytes

Some hydrophytes lack/have reduced roots/root hairs/root caps
do not need firm anchorage in water/wetland
presence of large air space parenchyma in roots/leaves; provides support for buoyancy
Presence of hairs on the leaves, to prevent blockage of the stomata
Stomatal pores occur only at the upper epidermis of the leaves to aid transpiration/loss of
numerous adventitious roots and root hairs; aid in the absorption of water/mineral salts
small size of the plant; for buoyancy/floating in water
waxy upper surface of the leaf, to prevent clogging of the leaf by water
long petiole/leaf stalk to support/ expose the broad lamina for photosynthesis
long flower stalk/pedicel; to expose the flower for pollination/ pollinating agents
presence of breathing roots/pneumatophores; for breathing/gaseous

Xerophytes

possession of thick succulent leaves/stems, for storing water
reduction of leaves to spines; to reduce water loss/rate of transpiration
thick waxy cuticle on epidermis; to reduce water-loss/transpiration
possession of a long tap root system; to obtain water from the great depth of the soil
presence of sunken stomata; to reduce water loss
reduced number of stomata; to prevent excessive water loss
possession of multiple epidermal layers, for water conservation/to reduce water loss.

QUESTION 04

(a) Explain the following terms:

(i) Test cross;

This is the crossing/mating of an organism of unknown genotype with a homozygous recessive/double recessive organism, to determine the genotype of an organism.

(ii) monohybrid cross;

Is a genetic cross between parents that differ in the alleles they possess, for one particular gene

(b) In a mango plant, the allele for bean-shaped seed is r and is recessive to round-shaped seed R. With the aid of a genetic diagram, determine the genotypes of the offspring if:

(i) a homozygous bean-shaped parent with a homozygous round-shaped parent;

(ii) A heterozygous bean-shaped parent is crossed with a heterozygous round-shaped parent.

Answer:

QUESTION 05

(a) Copy and complete the table below

Diseases

One effect

One remedy

kidney stones

· Abdominal pains;

· Decreased frequency of urination,

· Pain during urination;

· Presence of blood in the urine;

· Increased blood pressure.

· Drink plenty of water kidney transplant.

· Avoid foods rich in calcium/red meat/meat.

· Consult a physician.

Nephritis

· Oedema/swelling of feet and ankles;

· High blood pressure;

· Blood in urine

· Dizziness

· Back pain

· Fatigue/general weakness;

· Inflammation of the kidney tubules

· Consult a physician.

· Kidney transplant;

· Dialysis

· All food items must be washed and cooked properly.

· Drinking water boiled/ filtered/ sterilized.

Diuresis

· Thirst/dehydration occurs;

· High blood pressure may occur.

· Loss of appetite

· Weakness

· Fatigue.

· Nausea

· Loss of serum electrolytes.

· Consult a physician.

· Avoid fans/air conditioners in cold weather,

· Avoid excessive drinking of alcohol

(c) (i) What is an Estuarine habitat?

Estuarine habitat;

It is the place where a river enters to ocean/sea, into which the tides flow; fresh water mixes with salt water, to form brackish water.

(ii) Construct a food chain typical of an Estuarine habitat.

Typical food chain of an estuarine.

Phytoplankton (barnacles) => fish => bird
Detritus => worm => mollusk => bird
Detritus => shrimp => fish => bird

(d)(i) List the stages involved in the treatment of water for public consumption.

Answer:

Screening or filtration
Sedimentation
Coagulation/flocculation/addition of aluminum sulphate (alum)
Sterilization
Aeration
Storage

(ii) State three ways of controlling plant diseases.

Ways of controlling plant diseases

Chemical control/ use of fungicides/ nematicides/ bactericides/ pesticides
Biological control/ use of predators and parasites of insects/ pests to keep them in check
Breeding resistant varieties of crops
Planting genetically modified crops that can resist viruses/ bacteria transmitted by pests
Destruction of infested crops by burying/ deep burial/pruning of affected parts
Destruction of the alternate host
Adopt good management/ crop

(e) State four functions of a public health authority

Functions of a public health authority

Ensures the cleanliness of public places/markets/schools/playgrounds
Concerned with the proper disposal of refuse
Provides maternity clinics/health centers/nursing homes/family planning
Provides child welfare services
Provides medical inspection of schools
Register’s birth/death
Prevents and controls infectious diseases/ administers vaccination/ immunization/ inoculation
Informs the World Health Organization of the outbreak of infectious diseases
Ensures adequate provision of clean water to the public
Provides ambulance services
Provides quarantine services for plants/ animals/ humans
Gives a health certificate to travelers
Provides public health education/awareness of diseases
Inspects and certifies the health of animals and the cleanliness of slaughterhouses/abattoirs.

(f) State four ways of maintaining food hygiene in the community.

Ways of maintaining food hygiene:

Proper harvesting/ storage methods must be ensured to prevent damage to food items
Food items must be properly washed/ cleaned to prevent contamination
Food items must be properly cooked at appropriate temperatures
Kitchen/cooking areas must be kept clean, always/free from germs
Perishable food items must be properly preserved/ refrigerated
Proper personal hygiene must be observed by those handling food
Cooking utensils must be properly washed/ cleaned before and after use
Cooked/prepared food must be covered at all times
Proper disposal of unused/leftover food.

Join Enlighten Knowledge WhatsApp platform.

Join Enlighten Knowledge Telegram platform.

Follow our:
FACEBOOK PAGE.