WAEC Biology 2018 Practical Specimen Answers

WAEC Biology 2018 Practical Specimen Answers

Below are WAEC Specimen Practical Answers for Biology

Question 1

(a) Write the chemical equation for each of the following processes:

(i) aerobic respiration;

(ii) anaerobic respiration in plants;

(iii)anaerobic respiration in animals.[6 marks]

(b)State four functions which the liver of a patient suffering from cancer of the liver will not be able to perform, (4 marks]

(c)Make a diagram 8 - 10 ern long of a flame cell and label fully.[6 marks]

(d)Name one of appropriate hormone each responsible for the following conditions in plants

(i) ripening of fruits;

(ii) breaking dormancy in seeds;

(iii) weed control;

(iv)leaf fall [4 marks].

OBSERVATION: This was not popular question in this section and not many candidates attempted it. Those who attempted it scored poor marks.

Many candidates could not write the correct equations for aerobic and anaerobic respiration they rather defined the concepts and so lost the marks. Some candidates who attempted the equation could not balance it, most of them got the reactants correctly but could not correctly list the products ..

The expected answer was:

  (a) Chemical Equations for processes

  (i) Aerobic Respiration

      (ii)       Anaerobic respiration in plants

(Iiii) Anaerobic respiration in animals

C6H1206 -. 2CH3CH(OH)COOH + 2ATPlEnergy/150 k cal.

Most candidates who attempted this question could correctly state four functions which a cancerous liver would not perform and drew a fair diagram of the flame cell with adequate details however a number of candidates did not conform to the size specification, drew diagram with wooly lines, free-hand guidelines which were crossing. Spelling of labels wrongly also contributed to the poor performance on this question.

Most candidates could also state the hormones necessary for ripening of fruits, breaking dormancy in seeds, weed control and leaf fall but many of them could not score due to wrong spelling of hormones. Expected answers include:

Hormones responsible for

ripening of fruit - auxin/ethane/ethylene/ AA

breaking of dormancy in seeds - AuxiniGibberelins/cytokinins (kinta)

weed control- Auxin/2,4 - D/2,4 - Dichlorophenoxyacetic acid

leaf fall - Abscisic acid.

Question 2

(a) (i) Name two types of germination of seeds giving one example of each type. [4 marks]

(ii) Describe a simple experiment to demonstrate that oxygen, water and warmth are necessary for germination of seeds.  [10 marks]

(b) State two distinguishing features each of

(i)epiphytes;

(ii)parasites [4 marks]

(c) Give two examples of parasitic plants [2 marks]

OBSERVATION: This question was a popular question in this section and most candidates  attempted it. Most candidates had a fair idea of the two types of germination namely hypogeal and epigeal and could state examples but many candidates lost marks due to spelling errors and some candidates mixed up the example for each type. Only few candidates could describe a simple experiment to show that oxygen water and warmth are necessary for germination of seeds.

Majority of the candidates performed poorly in this sub-question. Many of them could not correctly name the necessary apparatus, give an outline of the experiment in a sequential manner and describe the control experiment. Expected answers include:

(ii) Experiment to demonstrate factors necessary for germination

Some dry cotton wool are placed at the bottom of each of conical flasks labeled A,B,C, and D.

in flask A, few/2 to 4 been seeds are placed on dry cotton wool; the flask is placed in a warm place;

in flask B the cotton wool is moistened together with the seeds in it;

test tube containing pyrogallic acid and caustic soda/pyrogallol is suspended in flask B; to absorb oxygen; flask B is put in a warm place;

in flask C a little water is placed on the cotton wool and seeds and it is placed in a warm place

in flask D a little water is poured on the seeds to moisten them and it is placed in the refrigerator;

the four flasks are observed for four to five days/few days; only the seeds in flask C germinated. This shows that oxygen, water/moisture and warmth are necessary for seed germination.

Most candidates could correctly state characteristic features of epiphytes and parasitic as well as give examples of parasitic plants. A few candidates however lost marks due to spelling errors.

Question 3

(a) Write short notes on each of the following:

(i) ecological niche;

(ii)population density;

(iii)climax community. [12 marks]

(b) Describe briefly the interactions between abiotic and biotic components of an ecosystem. [8 marks]

OBSERVATION: This question was another popular questions in this section and the performance of candidates on the question was just average.

Most candidates could correctly define Nitche and population density, but in defining population density forgot to state that the organisms they must be of the same species. Many candidates however could not defme climax community and so left the question unanswered.

Expected answers include:

(iii) Climax Community

Is established when a stable/unchanging community is attained in ecological succession; the community is in equilibrium with the environment; the vegetation reaches its highest development; and the same species of animals; and plants/organism re-occur from year to year.

Most candidates could not properly describe the interactions between the biotic and abiotic components of an ecosystem. Many candidates who attempted it limited their answers to merely naming the biotic and abiotic components. Expected answers were as follows:

(b) Interaction between biotic and abiotic components of an ecosystem

In an ecosystem the abiotic factors are non-living things (carbondioxide, oxygen, sunlight, soil and water etc.) while the biotic componenets are plants and animals. Green plants use carbon dioxide in the presence of sunlight; to produce carbohydrate/starch/food; Animals/herbivores feed on carbohydrates/plants; and release carbondioxide from respiration; decomposers breakdown dead plants/animals/organic matters to release nutrients to the soil; these nutrients are absorbed by plants for use in food production/photosynthesis; plants give out oxygen; during photosynthesis; which is used by animals for respiration

Question 4

(a)List four characteristics which can be genetically transmitted in humans[41 marks}

(b)(i) name two sites each in plants and animals where meiosis occurs.[4 marks]

(ii)State two differences between meiosis and mitosis.[2 marks]

(c)A woman with blood group 'A' (heterozygous) claimed that her son who has blood group '0' was fathered by Mr. James who has blood group 'A' (homozygous). With the aid of suitable genetic diagrams

(i)prove or disprove the woman's claim;

(ii)give reasons to support your answer. [10 marks]

OBSERVATION: This question was not a popular one and many candidates avoided it. Many candidates who attempted it did not score high marks. In stating inheritable characters many candidates stated skin, colour, hair colour, eye colour which earned them just one mark for colour. Some stated blood instead of blood group, anaemia instead of sickle cell anaemia and so lost marks. Many candidates could correctly name the site of meiosis in plants but in animals they named gonads rather than testes and ovary and so lost some marks.

A number of candidates cou1d correctly state the differences between mitosis and meiosis but

many candidates answer did not correspond and so they lost marks. Expected answers include:

DIFFERENCES BETWEEN MITOSIS AND MEIOSIS

MITOSIS                                                                   MEIOSIS

Nucleus divides only once                                         Nucleus divides twice

Number of chromosomes remains the same               Number of chromosomes is halved after

after division/diploid.                                                division/diploid.

Homologous chromosomes do not associate            Homologous chromosomes associate to form.

                                                                                    bivalents

Chiasmata are never formed                                        Chiasmata are formed

Crossing - over never occurs/no exchange of            Crossing - over occurs/exchange of

genetic materials                                                           materials occurs

Daughter cells identical to parent cell                        Daughter cells generally different from parent                                                                                           cell;

Two daughter cells are formed                                      Four daughter cells are formed

Chromosomes form single row at the equator              Chromosomes form double row at the  equator

Occurs in somatic cell                                                   Occurs in reproductive cell

Occurs in a sexual reproduction                                  Occurs in a sexual reproduction

Many candidates performed poorly in question 4(c) on the paternity of woman's child. Most

candidates cou1d not write the genotype of the parents namely AA and AO. They wrote Aa

instead of AO. They would not do the crossing. Many candidates stated that Mr. James was

not the father of the child but could not give reasons for their conclusion .

Expected answers were as follows:

                          WOMAN x         MAN

Blood group                 A                A

Phenotypes

Genotype               -     A0  x         AA

Gametes:                 A   0               AA

FI GENOTYPES      AO             AO           AA             AA

The Woman's claim is wrong

Reasons

Half their children are heterozygous blood group A and

Halfhomozygous blood group A

No child is group 0

Question 7

(a) Defme the term osmosis. [3 marks]

(b)            State two ways each in which osmosis is of importance to:

               (i)         plants;

              (ii)         animals. [4marks]

(c) A normal terrestrial plant was watered daily with a hypertonic solution for about seven (7) days          It was discovered that the plant was not doing well. Explain why.                                     [5 marks]

(d) (i)Explain briefly how marine organisms overcome the problem of high salinity in their environment?

     (ii) List four examples of organisms found in the benthic zone of a marine habitat. [ 4 marks]

OBSERVATION: This was the more popular question in this section and the performance of candidates was fair. Most candidates could properly define the term osmosis and state ways in which osmosis is of importance to plants but could not properly state the importance of osmosis to animals.

Expected answers were:

Animals

1. Re-absorption of water from glomerular filtrate;
2. Absorption of water by the colon;
3. Movement of water from one living cell to another.

Most of the candidates who attempted this question could state why a plant watered with hypertonic solution was not growing properly, but could not state how marine organisms overcome the problem of high salinity in their environment and seemed unfamiliar with organisms in the benthic zone of a marine habitat; some candidates rather gave examples of organisms found in fresh water habitats e.g. Tilapia, toad, etc.Expected answers include:

How Marine organisms overcome high salinity

1. They drink excess sea water to overcome high salinity restore/replenish water loss by osmosis;
2. Excrete excess salts out of their body through their gills;
3. Pass out large amounts of hypotonic urine;
4. Cartilaginous fishes maintain equal/similar osmotic pressure with sea pressure;
5. They possess scales on the skin to prevent permeability of water by osmosis.

Organism found in Benthic zone of marine habitat

1. Squids;
2. Octopus;
3. Latchet fish;
4. Angler fish;
5. Shark;
6. Corals;
7. Sea urchin;
8. Whales;
9. Mackerel;
10. Dolphin;
11. Crab.