2014 WASSCE; BIOLOGY PAPER 2 QUESTIONS AND ANSWERS.

Question 1

a. (i) List three characteristics of living

Answer:

• Movement/Locomotion,
• Excretion,
• Respiration,
• Reproduction,
• Irritability/Sensitivity/Response,
• Growth/Development,
• Nutrition/Feeding.

ii. Explain briefly the characteristics listed in (a)(i)

Answer:

Movement/Locomotion: Living things change the position of their whole body or parts of their body from one place to another in search of food, shelter, mates, protection, etc.

Excretion: This involves the removal/getting rid of waste products of cell metabolism. Metabolic waste is poisonous if allowed to accumulate, so it must be removed from the body.

Respiration: This is the breakdown of food substances by aerobic or anaerobic respiration to release energy needed for all processes of life.

Reproduction: This is the ability of living organisms to produce new individual of their own kind, this ensures the continuity of the species of organism.

Irritability/Sensitivity/Response: Response or reaction of the organism towards a change in the environment, to ensure survival.

Growth/Development: This is the irreversible increase in size and weight of an organism, which leads to complexity and maturation.

Nutrition/Feeding: The process involves obtaining or manufacturing food. It can be autotrophic or heterotrophic and utilize it for growth and maintenance/life processes.

b. In a tabular form, state four differences between plants and animals.

Plants	Animals
Plants can move only part of their body	Animals can move part or their whole body from one place to another.
Plants show indefinite growth	Animals show definite growth
Plants react slowly to external stimuli	Animals react quickly to external stimuli
They do not have a special sense organ	They have special sense organs
Plants have a cellulose cell wall	Animals do not have a cellulose cell wall
Plants store carbohydrates as starch	Animals store carbohydrates as glycogen
Growth is apical or lateral	Growth is diffuse or not uniform (intercalary growth)
They are autotrophic	They are heterotrophic

(c)(i) Name one organism that exhibits both plant and animal features.

Answer:

• Euglena
• Chlamydomonas

(ii) State four animal features and two plant features possessed by the organism named in (c)(i) above.

Animal features for Euglena

• Gullet for feeding
• Presence of a flagellum for locomotion in water
• Myones for movement
• Presence of pellicle that gives it a definite shape
• It has a contractile vacuole for osmoregulation and excretion

Animal features for Chlamydomonas

• Presence of a flagellum for locomotion
• Eye spot for sight
• Contractile vacuole for osmoregulation and excretion

Plant features for Euglena and Chlamydomonas

• Presence of chloroplasts containing chlorophyll for the absorption of light
• Definite shape
• Paramylon granules for the storage of starch
• Presence of pyrenoid for the production of paramylon granules

Question 2

(a) Define the following

(i) Elimination:

• This is the removal of undigested food from the body of a living organism.

(ii) Excretion

• This is the removal of waste products of metabolism from the cells/tissues of an organism; wastes may be toxic if they are retained in the body for a very long time.

(iii) Secretion:

• This is the production and release of substances useful to the body by specialized glands of living organisms.

(b) Describe the digestion of boiled fish in the gut of humans

• Boiled fish is a source of protein, which can be chewed and swallowed into the stomach.
• Digestion of proteins starts in the stomach.
• The stomach secretes gastric juice, containing pepsin, rennin, and hydrochloric acid;
• Pepsin in acidic medium acts on the boiled fish and converts it to a peptide.
• Peptides move into the duodenum, where pancreatic juice is secreted from the pancreas
• Undigested protein is acted upon by trypsin in an alkaline medium; peptides/peptones are formed.
• Erepsin finally acts on peptides/peptones in an alkaline medium;
• This is finally converted to amino acids, which is the end product of protein digestion.

(c)Make a diagram 8cm – 10cm long of a longitudinal section of a villus and label fully.

Question 3

(a) Explain briefly the following ecological terms:

(i) Biosphere:

• This is the total or whole area of the earth that can be inhabited by living things; it is a place where life exists.

(ii) Habitat:

• This is a place within an environment where an organism naturally lives successfully; it is a natural dwelling place of an organism.

(b) Describe the mode of nutrition in a named carnivorous plant.

Examples of carnivorous plants:

• Butterwort (Pinguicula),
• Sundew (Drosera),
• Venus flytrap (Dionaea)

The mode of nutrition of Butterwort/Sundew/Venus fly trap

• Carnivorous plants have green leaves and can manufacture their food by photosynthesis.
• They have roots to absorb water and mineral salts
• Use insects / other small animals as a source of nitrogen
• Carnivorous plants usually grow in places with little nitrogenous salts
• They have devices like sticky wet surfaces and sugary liquids for attracting and trapping insects.
• Once the insect/small animal is trapped, the plant secretes enzymes to kill and digest it.
• The soluble nitrogenous compounds are absorbed/assimilated by the plant as nitrogen

(c) State three reasons why the dispersal of fruits and seeds is important.

Importance of fruit and seed dispersal

• Prevents overcrowding of plants
• Prevents diseases from spreading among plant species
• Results in colonization of new areas with new plants
• Prevents undesirable competition for space/light/water, and nutrients
• It prevents total destruction of plants by natural disasters
• Prevent extinction of plants
• It ensures that less plants are eaten by predators.

(d) State six methods of conserving soil.

• Avoid overgrazing
• Avoid bush burning
• Application of manure/fertilizer to stabilize the soil
• Crop rotation/ growing crops on a piece of land in sequence
• Encourage afforestation/ cover cropping to cover and protect the soil
• Mulching of the soil to protect the soil against erosion
• Bush fallowing/shifting cultivation
• Afforestation
• Stripe cropping
• Contour ploughing
• Terracing

Question 4

(a)(i) Explain the term co-dominance

Co-dominance

• It occurs when both alleles in a heterozygous individual are fully expressed; both alleles exert their effects so that the hybrid has a phenotype that is different from that of its parents.

A survey to determine blood groups was carried out on 250 people living in a community.

The results are represented in the table below.

Blood Groups	Percentages
A	8.0
AB	14.0
B	32.8
O	45.2

 

(ii) Calculate the number of individuals with a co-dominant blood group

• Calculation of individuals with co-dominant blood group
• Co-dominant blood is AB

Calculation:

32.8% of 250

= 32.8/100 Χ 250

= 82 individuals /people

(iii) What is the total number of individuals in the table that can donate blood to an accident victim with blood group B?

The total number of individuals who can donate blood to blood group B

The total number of individuals is from groups B and O 14% of the population is blood group B

14% of 250

=  14/100 Χ 250

= 35 individuals/people.

45.2% of 250

= 45.2/100 Χ 250

= 113 individuals/ people.

Total number of people = 113 individuals of group O + 35 individuals of group B

= 148 individuals/people

Therefore, 148 individuals or groups can donate blood to the accident victim with blood group B

(b) A man whose blood group is heterozygote A is married to a woman whose blood group is AB. With the aid of a genetic diagram, suggest the possible blood group of their children.

Question 5

(a) State five reasons why animals move from place to place

Reasons why animals move from place to place

• To search for food
• Escape from predators
• To avoid danger
• Locate a new and favourable habitat
• To find mates for reproduction

(b) State one function each of the following structures found in plants;

Function of structures found in plants

(i) Epidermis:

• Protection of inner cells from injury;
• prevents excessive loss of water

(ii) Phloem

• Conduction of manufactured food, enzymes, and hormones from the leaves to all parts of the plants.

(iii) Sclerenchyma:

• Makes the plant flexible;
• Strengthens the stem
• Provides mechanical support

(c) Give two examples each of the following types of organisms:

• Parasitic plants
• Saprophytes

Examples of organisms:

Parasitic plants

• Viscum /mistletoe
• Dodder plant/ Cassytha
• Cuscuta

Saprophytes

• Bacteria
• Mucor
• Aspergillus
• Mushroom/ Agaricus

(b) State two adaptive features of plants that inhabit saltwater swamps.

Adaptive features of plants in saltwater swamp

• The presence of succulent roots/stems stores water to dilute the salt
• Presence of stilt root, for anchorage
• Some secret excess salt into swamps, to maintain the balance of body salt.

(e) State two factors each that result in

            (i) increase    (ii) decrease in population density

Factors that cause an increase in population density

• Increase in birth rate/natality
• Immigration
• Increase in the availability of food
• Age distribution
• Space

Factors that cause a decrease in population density

• Emigration
• Diseases
• High mortality rate
• A decrease in food
• Natural disaster
• Predation

(f) Mention four ways in which modern agricultural activities may threaten the survival of species.

Ways in which modern agricultural activities may threaten the survival of species

• Lack of afforestation practices
• Deforestation/commercial farming destroys the habitat of species
• Inappropriate fishing methods threaten the population of fish
• Overhunting of game reduces the population of species

(g) State three reasons why mitosis is important to living organisms

• Ensures retention of diploid condition
• Repair of tissues within organisms
• It transfers the exact genetic code from parents to offspring
• It ensures growth
• It is the basis for asexual reproduction as binary fission or budding.
• It ensures production of new cells for healing of wounds.

(h) State three causes of food spoilage

Causes of food spoilage

• Inadequate storage facility.
• Improper storage, which results in deterioration and spoilage of stored foods.
• Delay in transportation due to bad roads.
• Use of contaminated water to wash fruits.

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