2016 WASSCE; BIOLOGY PAPER 2 QUESTIONS AND ANSWERS.

QUESTION 01

(a) (i) List three forms in which living cells exist

Forms in which living cells exist

Single/free-living
Colony/colonial
Filamentous/filament
Part of a living

(ii) Give one example each of the forms listed in 1 (a)

Single/free-living

Amoeba
Chlamydomonas
Paramecium
Euglena

Colony/colonial

Eudorina
Pandorinallolvox
Sponges

Filamentous/filament

Spirogyra
Chladophora
Ulothrix
Zygnema
Oedogonium

Part of a living organism

cheek cell
onion cell
epidermal cell
parenchyma

(b) Make a diagram, 6 cm — 10 cm long, of a typical plant cell and label it fully

Diagram of a typical plant cell(c) (i) In a tabular form, state three differences between a plant cell and an animal cell.

Differences between a plant cell and an animal cell

PLANT CELL	ANIMAL
Has a cellulose cell wall / rigid	Lacks a cellulose cell wall
Has one large central vacuole	Has numerous/vacuoles
Has chloroplast	Lacks chloroplast
Contains starch granules in its cytoplasm	Contains glycogen granules in its cytoplasm
Usually larger in size	Usually smaller in size
Does not have a lysosome	Has lysosome
Does not have centrioles/centrosome	Has centrioles/centrosome
Has a regular / defined cell shape	Has an irregular/indefinite cell shape
Cytoplasm less dense	Cytoplasm is denser
Stores lipid as oil	Stores lipid as fat

(ii) State three similarities between a plant cell and an animal cell.

They both have:

cytoplasm;
nucleus;
vacuole;
mitochondrion;
Golgi body;
(smooth/rough) endoplasmic reticulum;
cell membrane/plasma membrane;
ribosomes

QUESTION 02

(a) In sequence, name the organs that constitute the alimentary canal of humans

Organs of the alimentary canal of humans in sequence

Mouth/buccal cavity
Oesophagus/gullet
Stomach
Duodenum
Ileum/jejunum/small intestine
Caecum/Colon/Large intestine
Rectum

(b) State:

(i) three structural differences;

(ii) three structural similarities between the alimentary canal of a bird and that of a human.

Structural differences between the alimentary canal of a bird and that of a human

BIRD	HUMAN
Beak present/mouth modified to beak	Beak absent/present of mouth
Teeth absent	Teeth present
Crop present	Crop absent
Gizzard present	Gizzard absent
Anal pore modified to cloaca	Anal pore modified to anus
Shorter alimentary canal	Longer alimentary canal
Appendix absent	Appendix present

(ii) Similarities in the alimentary canal of a bird and a human;

They both have:

a mouth,
oesophagus/gullet,
stomach,
duodenum,
small intestine,
large intestine,
caecum,
rectum

(c) Explain briefly how the dentition of herbivores is adapted for feeding

Adaptation of the dentition of herbivores for feeding

Elongated/curved incisors, for cutting grass/herbs
Thick horny pad; against which the lower incisors bit
Canines are absent/present of the diastema; allows the tongue to roll the cropped grass
Broad surfaces of the cheek teeth/molars; for grinding/chewing/masticating.
Ridges/furrows on cheek teeth/molars; for grinding/chewing/masticating

(d) State two roles of the pancreas in digestion

Roles of the pancreas in digestion

Produces pancreatic juices, which contain enzymes
Sodium bicarbonate in the pancreatic juice neutralizes the HCL from the stomach/producing an alkaline medium
Pancreatic amylase digests starch to maltose
Trypsin in the pancreatic juice digests protein into peptides/peptones
Lipase in the pancreatic juice digests fat droplets into glycerol and fatty acids

QUESTION 03

(a) (i) What is a habitat?

Habitat:

The natural dwelling place of an organism.
OR A place/locality where an organism lives successfully

(ii) Explain briefly three roles of a decomposer in an ecosystem.

Role of a decomposer in an ecosystem

Decomposers are organisms which bring about the decay of dead parts/whole plants/animals, to produce manure/humus.
They release nutrients into the soil, which are absorbed by the roots of plants, and are used to build up new plant tissues.
They help in nutrient recycling;
Also, they release offensive gases/odours which pollute the air.

(b) Explain briefly the energy flow in a freshwater habitat.

Energy flow in a freshwater habitat.

Common aquatic plants/Pistia/Spirogyra/any correctly named aquatic plant; using energy from the sun; photosynthesize/produce food;
The food is eaten by primary consumers/animals.
Small aquatic animals would be eaten by bigger aquatic animals/secondary consumers;
Tertiary consumer/a much bigger fish/any correctly named fish will feed on the secondary consumer,
In the process of feeding, energy flows from one trophic level to another, and decreases progressively;
Dead animals/plants decompose; energy is lost.

(c) (i) State three harmful effects of microorganisms on plants.

Harmful effects of microorganisms on plants

They cause diseases
They can cause undesirable qualities in plants/plant products
They cause spoilage
Reduction in yield

(ii) State six beneficial effects of microorganisms to humans

Beneficial effects of microorganisms on humans

Bacteria/decomposers help to decay/decompose dead organisms to release nutrients
Bacteria are used in cleaning/mopping up oil spillage
Used in the fermentation of foods/cocoa beans/garri/locust beans/kenkey production
Used to make vinegar
Used in making alcoholic beverages/wine/beer/spirits
Used in making some antibiotics/penicillin
Used in the manufacture of insulin
Used in making cheese/yoghurt/bread/Single Cell Proteins
Used in making flax/tanning of leather;

QUESTION 04

(a) (i) Explain the term agglutination as used in blood transfusion.

Agglutination

The clumping together of antigens of red blood cells/RBC with the corresponding antibodies in the plasma, of incompatible blood groups/wrong blood group.

(ii) The table below represents blood transfusions between blood donors and recipients.ANSWER:

DONOR		RECIPIENT
		A	B	AB	O
	A	+	–	+	–
	B	–	+	+	–
	AB	–	–	+
	O	+	+	+	+

(b) Explain how each of the following organisms is adapted for obtaining food.

(i) Mosquito larvae

(ii) Dodder plant

(iii) Grasshopper

Mosquito larvae

Possess a pair of ciliated mouth brushes for creating a water current to carry water with food particles into the mouth.
Its mouth brushes, filters food out of water and sweeps it into the mouth.

Dodder plant

Possess haustoria, for penetrating host plant tissue to obtain food/water.

Grasshopper

Possess mandibles/heavy toothed jaw-like structures, for cutting/crushing food/plant materials/vegetation;
Possess maxillae, for directing food to mandibles/cutting/grinding food;
Labrum, for holding food/plant materials/vegetation;
Labium, for guiding foods/preventing them from falling

QUESTION 05

(a) State two differences between tactic and nastic movements in plants

Differences between tactic and nastic movements in plants

TACTIC MOVEMENT	NASTIC MOVEMENT
movement of the whole organism / entire plant	movement shown by part of a plant
movement is directly towards/from the stimulus	Non-directional movement
stimuli consist of light/heat/chemical	The stimulus is touched/turgor pressure

(b) Give two examples each of organisms that show:

(i) tactic movement

(ii) Nastic movement

Tactic movement

Volvox
Chlamydomonas
Euglena
Earthworm
Tilapia

Nastic movement

Morning glory
Mimosa
Pride of Barbados (Caesalpinia)
Four o’clock plant
Morning flower
sunflower
Desmodium
Clove

(c) (i) State three ways of caring for the mammalian skin.

Care of the skin

Eating a balanced diet rich in vitamins A/B2/E
Engaging in regular exercise
Washing the skin with clean water and soap daily;
Drinking a lot of water
Moisturising/rubbing the skin with lotion/cream
Avoiding excessive exposure to ultraviolet rays/radiation
Avoiding bleaching creams/harsh chemicals
Wearing clean clothes next to the skin
Protect the skin against

(ii) List three stimuli to which the mammalian skin is sensitive.

Stimuli to which the mammalian skin is sensitive

Touch
Pressure
Heat
Cold
Pain
Chemicals

(d) State five effects of high temperature on a terrestrial habitat.

Effects of high temperature on terrestrial habitat

Causes a high transpiration rate in plants
Plants wither/wilt
Leads to a high rate of metabolism in both plants and animals
There is a high rate of decay of organic matter
Leads to a high rate of growth and a shorter length of life cycle in the toad/housefly
Makes poikilothermic animals look for shelter from heat/hibernation
There is a high rate of water loss in animals/sweating/perspiration
Leads to a high incidence of bushfires
Migration/emigration

(e) (i) What is courtship behaviour in animals?

Courtship behaviour in animals

A type of behaviour/instinctive action in animals that plays an important role in attracting a compatible mate/ opposite sex, of the same species, for copulation/sexual reproduction

(ii) List three courtship behaviours in animals.

Courtship behaviours in animals

Pairing
Territoriality
Seasonal migration
Smell/release of attractive sex hormones/odour
Display of prominent colour patterns
Mating calls/croaking/vocal displays/sound signal
Dancing/attractive

(f) Name three organisms that carry out the holozoic mode of nutrition.

Examples of organisms that carry out a holozoic mode of nutrition

Goat
rat
lizard
frog
bird
human
pitcher plants;
sundew;
bladder

(g) Explain briefly how fingerprinting can be used to detect crime.

Use of fingerprinting in crime detection

No two individuals have the same, identical pattern, contour of fingerprints; hence, it is used for crime detection
Fingerprints left behind by a criminal at the scene of a crime, door, table, or weapon, or on a victim provide a valuable clue in the detection and subsequent arrest of a criminal.
The fingerprints left on the scene of the crime are photographed,
The crime suspect’s fingerprints are taken and compared with the fingerprints at the scene of the crime
If they match, then the suspect is the criminal.

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