2019 Biology WAEC Theory Past Questions

2019 Biology WAEC Theory Question 1

(a) (i) Complete the table below with the respiratory surface of each of the listed organisms.

Answer:

(ii) State five characteristic features of respiratory surfaces in organisms.

Answer:

• Large surface area to aid easy diffusion of gases
• Thin-walled or thin body surface to shorten diffusion distance and make diffusion easier and faster.
• It must be permeable to allow gases to pass in and out of them.
• Respiratory surfaces must be highly vascularized i.e. equipped with a network of blood capillaries to bring in or take away diffused gases.

(b) Make a drawing, 4cm – 6cm long of the respiratory organ in Tilapia and label fully.

Answer:

Question 2

The table below shows the percentage composition of fat and protein in six different meat types. Study it and answer questions 2(a) to 2(d).

(ai)  Which two of the meat types may be recommended for an obese patient?

Answer:

Meat type that may be recommended for an obese patient is A, D.

(aii) State one reason for the answer in 2 (a)(i).

Answer:

This is because meal types A and D have lower fat content compared with other meat types and are rich in protein.

(bi) Which two of the meat types would provide the most energy?

Answer:

Meal types that provides most energy is B, C

(ii) State two reasons for the answer in 2(b)(i)

Answer:

This is because they have the highest fat composition so when oxidized would release much energy.

(ci) Which three of the meat types could be recommended for a child suffering from kwashiorkor?

Answer:

Meat types that could be recommended for a child suffering from kwashiorkor is A, C, D, and E.

(cii) State one reason for the answer in 2(c)(i).

Answer:

This is because a child suffering from kwashiorkor is deficient in / lacks an adequate amount of protein / needs more protein, and meat types A, C, D, and E have high protein contents.

(d) Which of the meat types would most likely be suitable for:

(i) An inactive teenager;

Answer:

Meat type most suitable for an inactive teenager is A, B, C, D, E, F.

(ii)  A 70-year old human?

Answer:

Meat type most suitable for a 70-year-old human is A, D

(e) Which other class of food provides energy?

Answer:

Carbohydrate

(f) State three uses of fat in the human body.

Answer:

• Provides insulation
• Generates heat
• Provides energy
• Protects vital organ
• Forms part of the cell membrane (phospholipid) 
• Smoothens the skin
• Forms solvent for some fat-soluble vitamins i.e. vitamins A, D, E, K

(g)  Describe briefly the procedure for testing for fat in a meat sample using a piece of white paper.

Answer:

• Meat sample is rubbed against a piece of white paper and allowed to dry.
• A translucent spot on the paper confirms the presence of fat in the meat sample.

2019 Biology WAEC Theory Question 3

(a) Classify the following biological associations under the headings in the table below:

(i) Remora and shark;
(ii) Lichen
(iii) Cattle and White Egret;
(iv) Tapeworm in the gut of humans;
(v) Flowers and Honeybees
(vi) Mistletoe and Cacao plant

Answer:

(b) (i) State three adaptive features of parasites.

Answer:

• Possession of specialized organs e.g. suckers for attachment to the body surface of the host.
• Possession of specialized piercing and sucking mouthparts for fluids, blood, or plant juices.
• Some are hermaphrodites which give them the ability to reproduce rapidly and easily in large numbers.
• Ability to produce a large number of eggs to propagate their species.
• Presence of large surface area for absorption of digested food.
• Possession of special structures to withstand harsh environments.

(ii) State two effects of parasites on their hosts.

Answer:

• Can lead to loss of blood
• Can lead to Stunted growth
• Can devalue the worth of animal skin/hides
• Reduces the value of farm animals
• Can lead to death
• Can lead to low resistance to diseases in the host
• Causes diseases/injury/harm

(c) (i) What are Saprophytes?

Answer: Saprophytes are organisms that lead feed on dead decaying/decomposing organic matter.

(ii) Give four examples of saprophytes.

Answer:

2019 Biology WAEC Theory Question 4

Use the information below to answer questions 4(a)(i) and 4(a)(ii).

Hb^A represents normal haemoglobin, Hb^S represents sickled haemoglobin.

(a) A female heterozygote for sickle cell married a Sickler. With the aid of a genetic diagram, determine the:

(i) Possible genotypes of their offspring;

Answer

(ii) Phenotypic ratio of the offspring

Answer

2:2 or 1:1 / Ratio of sicklers to non-sicklers.

Since Hb^AHb^S is a carrier while Hb^SHb^S

is a sickler, two out of four offspring are carriers while the other two are sicklers.

(b) Explain briefly the reason why a Rhesus-negative woman married to a Rhesus-positive man might lose her second pregnancy.

Answer

Rhesus-negative mother has no antigen on the surface of her Red blood cells. The husband has antigen on his red blood cell.

During her first pregnancy, the child carries a positive Rhesus factor. The Rhesus factor enters the mother’s bloodstream. Due to rupture of the placenta, blood seeps into the mother’s blood causing it to develop anti-rhesus antibodies, causing agglutination in a small proportion of foetal blood cells.

In the second pregnancy, the child might be rhesus positive, the child carrying rhesus positive suffers massive destruction of red blood cells (erythroblastosis fetalis) which might result in a miscarriage of the second child. 

(c) Name two examples of features in animals that support the theory of use and disuse of body parts as used by Lamarck.

Answer

• Long neck of a giraffe
• Smaller wings in penguins
• Lost legs of snakes
• Long legs of Heron
• Webbed fact of ducks, frogs, geese

(d) List three structures in mammals that are vestigial.

Answer

• Vestigial organs of mammals
• Appendix in humans
• Reduced coccyx in man/caudal vertebrae
• Ripples in males
• Hairs on the chest
• Wisdom teeth

2019 Biology WAEC Theory Question 5

(a) Explain briefly the importance of the following factor and organisms in the nitrogen cycle:

(i) Lightening

Answer:

When lightening occurs, nitrogen reacts with oxygen in the air to form nitrous oxide/oxides of nitrogen which is further oxidized to form nitrogen (iv) oxide.

Nitrogen (iv) oxide dissolves in rainwater to form nitric and nitrous acids that fall to the ground when it reaches the soil, it combines with bases/mineral salts to form nitrates, which plants absorb.

(ii) Nitrosomonas

Answer:

This is a nitrifying bacterium in the soil that converts ammonia to nitrates in the soil.

(iii) Azotobacter

Answer:

This is a nitrogen-fixing bacterium in the soil that converts nitrogen in the soil into ammonium compounds and protein in the soil.

(b) Name the excretory organ in:

(i) Insects
(ii) Earthworm

Answer:

Insects – Malpighian tubules
Earthworm – Nephridium

(c) Explain briefly the following diseases:

(i) Hepatitis

Answer:

• It is the inflammation of the liver cells. 
• It can arise from bacteria or viral infection.
• It is an autoimmune disease resulting from excessive consumption of alcohol.

Symptoms

• • Jaundice
  • Fatigue
  • Loss of appetite
  • Muscle aches/pains
  • Flu
  • Fever
  • Nausea
  • Dark coloured urine

(ii) Kidney stones

Answer:

Kidney stones are small solid/crystals of concentrated minerals or uric acid found in the urine. They are formed if there is excessive loss of water or insufficient water intake so that the solubility of minerals such as calcium phosphate or calcium oxalate in the urine is reduced. A high level of amino acids can lead to kidney stones.

Bacteria may be trapped in the kidney tubules as the kidney stones get bigger.

Symptoms

• Sharp pains at the flank of the back
• Frequent urination
• Nausea
• Sweating

Treatment

Kidney stones can be treated by medications, change in diet of food rich in calcium, sugary, and drinking plenty of water.

(d)(i)  State three effects of lack of sense receptors in the skin of humans.

Answer:

Humans will not be able to sense/feel/perceive external stimuli in the environment such as pain, touch, pressure, changes in temperature, and dangers which could lead to death.

(ii) List three layers of the epidermis in the skin of humans

Answer:

• Cornified layer or stratum corneum
• Granular layer or stratum granulosum
• Malpighian layer or stratum malpighian

(e)(i) What is metamorphosis?

Answer:

This is the gradual development of certain organisms from the egg to an adult stage involving three to four stages.

(ii) State the type of metamorphosis exhibited by each of the following insects listed in the table below.

Answer: