Question 1 |
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(a) (i) List three characteristics of living organisms. [3 marks] (ii) State four animal features and two plant features possessed by the organism named in 1(c)(i) [6 marks] |
ANSWER
Explanation of characteristics of living Organisms
(ii) Movement
Living things change the position of the whole body/parts of the body;
from one place to another; in search of food/shelter/mates, etc.
Excretion
This involves the removal/getting rid of waste products of cell metabolism;
metabolic wastes are poisonous if allowed to accumulate.
Respiration
This is the breakdown/burning of food substances; by aerobic/anaerobic respiration;
to release energy needed for all processes of life.
Reproduction
This is the ability of living organisms to produce new individuals of their own
kind; this ensures the continuity of the species of an organism.
Irritability
Response/reaction of organisms; towards changes in the environment; to ensure
survival.
Nutrition
The process involved in obtaining/manufacturing food; can be autotrophic/
heterotrophic; and utilizing it for growth and maintenance/life processes.
Growth
This is the irreversible increase; in size and weight of an organism; which
leads to complexity and maturation.
Competition
Ability of organisms to struggle; for all necessity of life; to survive in their
environment.
Adaptation
Ability of organisms to adjust; to changes in environment; for survival.
Life span/Death
All living organisms have definite period of existence; all organisms die.
(b) Differences between plants and animals
Animals | Plants |
– Move from place to place/locomotion; move with the whole body | Are fixed/do not move from place to place; and move only parts of the body, root/stem/leaves; |
| Autotrophic mode of nutrition/manufacture their own food using the energy from the sun; |
| Chlorophyll/chloroplast present; |
| Sense organs absent; |
| Has a cell wall made of cellulose; |
| Growth is unlimited/indefinite; growth is apical or terminal; |
| Store carbohydrate as starch; |
| No special excretory organs; |
| Response very slow/long termed; |
| No respiratory organs; |
Note: Points must correspond to score.
No tabulation minus (-) 1 mark.
(c)(i) Name of organism
Euglena/Chlamydomonas
Note: Spelling must be correct to score.
(ii) Animal Features
For Euglena For Chlamydomonas
– Gullet for feeding; – Flagella;
– Has flagellum for locomotion in water; – eye spot;
– Myonemes for movement; – contractile vacuole
– Has pellicle that gives it a definite shape;
– Has eye spot to detect light intensity;
– Has contractile vacuole for osmoregulation and excretion.
Plant features
– definite shape;
– has chloroplasts containing chlorophyll used to absorb light;
– Paramylum granules;
– Pyrenoid.
Question 2 |
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1.(a) Define the following terms: |
ANSWER
(a) Definition of terms
- Elimination: Removal of undigested food; from the body of living organisms.
Excretion: Removal of waste products of metabolism; from the cells/tissues
of an organism; may be toxic if retained in the body.
- Secretion: Production and release of substances; useful to the body; by
specialised glands of living organisms.
(b) Digestion of Boiled Fish in the Gut of Humans
Boiled fish is a source of protein; chewed and swallowed into the stomach; digestion
of protein starts from the stomach; stomach secretes gastric juice; containing pepsin,
rennin and hydrochloric acid; pepsin in acidic medium acts on the boiled fish and convert
it to peptides; peptides move into the duodenum / small intestine; into which pancreatic
juice is secreted; undigested protein is acted upon by trypsin in alkaline medium; into
peptides/peptones; erepsin finally acts on peptides/peptones in alkaline medium; and
converts it into amino acids.
(c) Diagram of Villus
Title (TL) – Longitudinal section of villus
Size (Sz)(8 – 10cm long)
Quality (Q)
Clarity of lines (CL)
Neatness of Labels (NL)
Details (D)
Epithelium layer shown (EL)
Conical shape of villus (One cell thick) (CV)
Labels (L)
Epithelium layer, blood capillary, lacteal, lymphatic vessels, goblet cells,
venule, arteriole, Crypt of Lieberkuhn, cells of Paneth, Muscularis mucosa.
NOT AVAILABLE
Question 4 | ||||||||||
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A survey to determine blood groups was carried out on 250 people living a community.
(a) (i) Explain the term co-dominance . [2 marks] (b) A man whose blood group is heterozygous A is married to a woman whose |
ANSWER
(a)(i) Codominance
Codominance occurs when both the alleles in an heterozygous individual are fully
expressed; that is both alleles exert their effects so that the hybrid has a phenotype;
that is different from what the parents exhibit.
(ii) Calculation of Individuals with Co dominant blood group
Mention of codominant blood group is AB
Evidence of Calculation
32 .8% of 250
OR
32.8 x 250
100
= 82 individuals/people
(iii) Total number of individuals that can donate blood to blood group B
The total number of individuals will be from groups B and O
- 14% of the population is Blood group B
14% of 250
OR
14 x 250
100
= 35 individuals/people
- 45.2% of the population is blood group O
45.2% of 250
45.2 x 250 = 113 individuals/people
100
- Total number of people = 113 of group O
35 of group B
148 individuals/people can donate blood to the
accident victim in B
OR
The Total number of individuals from (B and O) blood group B and O
- 14% + 45.2% = 59.2%
- 59.2% of 250
= 148 people/individuals
(b) Crossing
OR
Punnet Square – scoring/ (Punnet Square)
NOT
ANSWER
Question 6 |
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(a) State five reasons way animals move from place to place. [5 marks] (i) epidermis: (i) parasitic plants; (ii) saprophytes. [4 marks] (i) increase: (ii) decrease, in population density. [4 marks]
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ANSWER
6(a), (b) and (c) satisfactorily. Majority could not
completely express themselves in other questions
The expected answers are:
(c) Examples of Organisms
(i) Parasitic plants
Viscum/Mistletoe; dodder plant/Cassytha; Cuscuta; Phytophthor;
Peronospora (any correctly named example) Note: Spelling must be correct to score
(ii) Saprophytes
Bacteria; fungi/Rhizopus, Mucor, Aspergillus; Mushroom/
Agaricus (any correctly named example)
Note: Spelling must be correct to score
(d) Adaptive features of plants in salt water swamps
– succulent stem/root/store water; to dilute the salt;
– presence of pneumatophores/breathing roots; for breathing atmospheric
– air/oxygen;
– presence of stilt roots; for anchorage;
– viviparous seedling; to ensure their survival/continuity;
– some secrete excess salt into swamps; to maintain balance of body salt.
(e) Ways modern agricultural activities may threaten the survival of species
– Deforestation/commercial farming destroys habitats of species;
– Destruction/loss of natural vegetation/habitat;
– Over hunting of games reduces population of species;
– Improper/Indiscriminate application of chemical/
salanization/eutrophication/pesticides destroys species;
– Lack of afforestation practices;
– Inappropriate fishing methods threaten the population of fish.
(f) Reasons why mitosis is important to living organisms
– It ensures growth;
– Involved asexual reproduction e.g fission, budding, spore formation;
– Ensures retention of diploid condition;
– Repair of tissues within organisms;
– Transfer of exact genetic code from parents to offspring.
(g) Causes of food Spoilage
– Microbial attacks by bacteria or fungi/or saprophytic action;
– Pest attack by beetles, weevils that destroy stored grains;
– Improper storage which results in deterioration and spoilage of stored foods.
– Destruction of stored fruits and meat by some worms, usually larva of flies;
– Delay in transportation due to bad roads;
– Lack of market facilities for the commodity;
– Poor harvesting method/damage to fruits/vegetables/tubers during harvesting;
– Poor unhygienic handling/processing/exposure to dust;
– Storage in contaminated containers;
– Use of contaminated water to wash food.
