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BUTERE EAST ZONE EVALUATION TEST
BIOLOGY 231/2
MARKING SCHEME
1. (a) (i) Sweep net;
(b) Pouter;
(b) (i) Synthesis of ribosomes;
(ii) Destroy worn out cell organelles/cells;
(iii) Synthesis of protein;
(c) Plant cell
Animal cell
- Has cell wall;
- No cell wall;
- Store carbohydrates inform of starch;
- Stores carbohydrates in form of glycogen;
- Regular in shape;
- Irregular in shape;
- Has a peripheral nucleus;
- Ha a centrally placed nucleus;
- Large central vacuole;
- Small vacuoles scattered in the cytoplasm;
- Some have chloroplasts;
- No chloroplasts;
2. (a) (i) A- Root nodules;
D – Root hairs;
(ii) – Nitrates;
(iii) – It’s the conversion of free nitrogen in air into nitrates;
(b) (i) – It’s the linear flow of energy through different trophic levels in an ecosystem;
(ii) – Primary consumers;
(iii) – Pyramid of numbers – to be drawn to scale;
Scale 1 cm rep. 100 organisms.
Nile perch (100)
Tilapia (300)
Planktonic algae (1000)
5
4
3
2
1
0
1
2
3
4
5
(c) – There is gradual decrease in numbers due to energy loss through respiration, defeacation, urination;
3. (a) – Homodont – dentition with one type and shape of teeth;
- Heterodont - dentition with different types and shape of teeth;
(b) (i) 30 teeth;
(ii) - Herbivorous/herbirory;
(iii) - Lack upper incisors and canines;
(c) – Mortar tooth – has broad surface with cusps;
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Function: Increases surface area for grinding;
- Carnassial tooth – sharp edge for shearing;
- Slicing flesh/for crushing bones,
Diagram – double walled.
4. (a) (i)
- Well cell membrane. (1 mk)
Labeling – cell membrane
- vacuole (2 mks)
– The salt solution was hypertonic to the cell sap; the vacuole lost water to the solution by
(ii)
osmosis; hence reducing in size;
(iii)
- Plasmolysis;
5. (a) - Scientific system of giving organisms two names; Generic and specific names;
(b) - Identification/placing them in their correct groups;
- To understand the evolutionary relationship between organisms;
- To arrange information about living organisms in an orderly manner for easy study/avoid
confusion;
(c) Insecta
Arachinida
- 3 pairs of limbs;
4 pairs of limbs;
- 3 body parts;
2 body parts;
- Gaseous exchange through
Gaseous exchange through book lungs;
tracheal system;
6. (a) Scale – 1 x 2 = 2 mks
Plotting – 1 x 2 = 2 mks
Curves – ½ x 2 = 1 mk
Axes – ½ x 2 = 1 mk
Identification = ½ x 2 = 1 mk
(Total = 7 mks)
(b) (i) – Frog;
- Body temperature increases with increase in environmental temperature; frogs are
ectotherms/poikilothem; hence cannot control their body temperature by physiological means;
(ii) Student;
(c) (i) – High osmotic pressure stimulates the hypothalamus /osmoreceptor cells that send an impulse to
the pituitary gland to secrete ADH; which is transported to the kidney tubules; making them
more permeable to water; more water is reabsorbed into the blood stream lowering the osmotic
pressure; back to normal;
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Biology 231/2
(ii) – Deamination – the removal of amino group from an amino acid in the orinthine cycle;
7. (a) - The root hairs grows between the soil particles surrounded by a film of water/soil solution; The sap
in the root hair has higher osmotic pressure than the soil solution; Water is drawn into the root hair
by osmosis; This dilutes the cell sap in epidermal cell; relative to the sap in the adjacent cortical
cells; Because of this, water moves into the adjacent cortical cells; until it reaches the xylem
vessels; Within the leaf cells; some water is used in the manufacture of food; and some vapourises
when the temperatures are high; gets into the intercellular air spaces; and diffuse out of the leaf;
through the stomatal opening; into the atmosphere; in a process called transpiration;
(Total 17 mks)
(b) Mechanisms of translocation of manufactures food.
- Active transport;
- Mass flow;
- Surface spreading;
- Cytoplasmic streaming;
(Any three correct points = 3 mks)
8. (a) Characteristics of respiratory surfaces.
- Thin epithelium for faster diffusion of gases;
- Folded or branched creating large surface are for rapid diffusion of gases.
- Have rich supply of blood capillaries for fast transport of gases to and from tissue;
- Have moist surfaces to enable diffusion of gases
(1 mk each = 4 mks)
(b) Adaption of mammalian lungs to their functions;
- Lungs are surrounded by a 2 – layered membrane called pleural membrane; which protect the lungs
from mechanical damage; between the two layers is a cavity called pleural cavity; filled with
pleural fluid; that lubricates lungs; protecting it from friction/abrasion; by inner walls of the thorax
as they are inflated and deflated; The lungs have a dense network of blood capillaries; that increase
surface area; over which gases diffuse for transportation; The lungs have numerous air
sacs(alveoli); that store air, and provide surface over which gaseous exchange takes place; The
lungs are elastic; hence expand and contract to hold and expel large volume of air; The lungs are
located in the rib cage; that cushions them from mechanical damage;
Total: 17 points
Max: 16 mks)
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Biology 231/2