TERM 2 2025

BIOLOGY PAPER 1

MARKING SCHEME

1. (a) (Provide) site for protein synthesis;

(b) Site for packaging and transport of glycoproteins;
2. (a) T – Xylem vessel;
(b) S – Endodermis;
(b) Root hair cell;
- Narrow and elongated to increase surface for absorption of water and mineral salts.
- Thin to reduce diffusion
3. (a) A- Concentration of salt was isotonic; to that of the cytoplasm of Red blood cells hence no change;
(b) B – most cells haemolysed; due to hypotonic salt solution;
4. (i) Gives evidence on the type of organisms that existed along time ago; and shows morphological
changes that have occurred;
(ii) Gives evidence based on morphological resemblance between embryo of different vertebrates
species during early stages of development;
drawing length
5. Magnification =
Actual length
Drawing length = 1000µm
Mg =x40000
drawing length
Actual length =
mg
100
=
40000

=0.025µm

6. Have large air spaces for buoyancy.

7. (a)Glycoge;
(b) POLYACCHARIDE MONOSACCHARIDE
– Not sweet - Sweet
– Insoluble in water - Soluble in water
–Many monomers - One monomer
8. (a)Fungi(2mks)
(b)Cephalothorax(1mk)
(c) Rhizoids for anchorage; Thalloid or differentiated (2mks)
9. (a) Presences of antibodies; and white blood cells in blood that kill /destroy pathogens;
(b) High concentration of oxygen in pulmonary vein /higher concentration of carbon oxide in pulmonary
artery;
10. Haemocoel Trachea Ostia Spiracles
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 √ Naming
√ For the arrows direction
11. (a) Diffusion
(b) Starch changes into blue - black
(c) iodine molecular diffused from the beaker into the visking tubing (high to low)
(d) Iodine moleculars are small in size hence passes through the visking tubing is a semi – permeable
membrane.
12. (a) Mutation is spontaneous/sudden change in the (DNA) genetic make up of an organism.
(b) Baldness;
– Hairy pinna/hairy ears; (Rej.hairy nose)
– Masculine x –tics/Ducheme muscular dystrophy;
13. High altitude; low concentration of oxygen; hence stimulates the body to produce more haemoglobin for
better transport of oxygen increasing respiration ; that increases energy production required in the race.
14. (i) Density refers to the number of individuals per unit area;
(ii) Dispersion is the spread of organisms in a habitat;
(iii) Population growth refers to the rate of increase in numbers in of an organism;
15. (i) Microbiology study of microscopic organisms
(ii) Genetics – study of inheritance and variations
16. (a) (i) Mitochondrion; rej plural
(ii) Site for energy production; Site for respiration
(b) Inner membrane folded to form cristae that increase surface area for attachment of respiratory
enzymes.
(c) Muscle cell/ kidney/sperm/meristematic
17. (i) Stored food is being broken down by enzymes; and used to produce energy for growth;
18. (ii) First foliage leaves have been formed that increases the rate of photosynthesis; and hence increase in
growth;
19. (a)Process of transfer of pollen grains from the anthers to stigma of a flower of same species;
(b) Protandry and protogyny/dichogamy
Self – sterility/incompatility
Heterosty
Dioecius (1st three)
20. Avoid indiscriminate sex;
Avoid practices that expose one to risk of infections e.g sharing contaminated instruments; /drug
abuse/wife inheritance
Use of condoms
Diagnosis (1st two)
21. (a) Outer membrane
(b) B;
(c) A;
22. (a) (i) Homeostasis;
(ii)Excretion;
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 (b) (i) Treatment of malaria;
(ii) Used as meat tenderizer;
(iii) Used as local anaesthecia;
23. (a) Type of reproduction where a group of cells arise from a single individual cell without fertilization;
(b) The replacement of faulty gene with normal ones aimed at correcting genetic disorders;
24. (a) Secondary growth/secondary thickening;
(b) Primary phloem;
(c) Divide by mitosis to form secondary phloem and secondary xylem;
25. (a) Fungi; (1mk)
(b) (i)F - Bear spores; (2mks)
G – Anchor the fungi onto substratum / absorption of water and minerals;
(c) Chitin; (1mk)
26. (a) Gives the type of respiration;
Gives the type of substrate being respired
(b) (2mks)
R.Q = Volume of carbon (IV) oxide produced;
Volume of oxygen used
= 20
20

= 1.0;

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