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Biology Paper 2

SECTION A (40 Marks)



A –Root cap;

C – Phloem;

E- Root hairs;


(i). Cell divisions;

(ii). Thin cell walls;

(ii). Dense cytoplasm;

(iv). Lack sap vacuoles;

(c). In zone 2 cells elongate while in 3 cells differentiate;

8 marks


(a). Both Rr;

(b). Parental genotypes Rr x Rr; Possible genotypes RR or Rr;

(c). Lack of variations; Inheritance of undesirable genes (not expressed in heterozygous state);

9 marks



(i). Thigmotropism /haptotropism

(ii). Less auxin produced on the side in contact than side away from contact; Higher concentration of auxins on side away from contact causes more growth.






- Expose leaves/shoots in position for maximum absorption of light for photosynthesis.

-Enables roots to seek water.

-Enables roots to grow deep in soil for anchorage.

- Enables pollen tube to grow towards embryo sac to facilitate fertilization.

-Enables plants to obtain mechanical support especially in weak stems.

9 marks



(i). Walls of stomach;

(ii). Stimulates the secretion of gastric juice.

(b). Presence of food in stomach;


(i). P – Small intestines /ileum;

(ii) Q – Large intestines /colon;

(d). Folding of the inner walls of P and not Q.

6 marks



X - Nucleus;

Z - Cilia;

(b). Oviduct;


-Remove dust particles/bacteria / micro-organisms / pathogens;

-Moves ovum towards uterus;


-Trap dust particles entering respiratory tract;

-Trap bacteria/micro-organisms entering respiratory tract;

-Moistens inhales air;

8 marks

SECTION B (40 Marks)

Answer question 6 (compulsory) and either question 7 or 8

(a). On graph paper;

(b). Conc of progesterone on day 10 is 46;

(c). Oestrogen; it stimulates the release of luteinizing hormone;


(i). Day 14;

(ii). Conc of oestrogen is highest; High levels of oestrogen stimulates secretion of LH;


(i). Conc. of progesterone increases from day 14; and highest on day 21; because after ovulation (on day 14) corpus lnteum begins to produce progesterone;

(ii). Conc of progesterone decreases; because corpus lnteum degenerates when there is no fertilization.


Axile / centrial




Free central

20 marks


The afferent arteriole supplies blood to glomerulus; The afferent arteriole has wider diameter than efferent arteriole;

This causes high pressure; leading ultra-filtration; of Glucose, amino acids, salts; urea and water filter into Bowman’s capsule; to form glomerular filtrate; WBC/RBC/ Blood cells, proteins are too large to pass through the capillary wall hence Remain in blood capillaries;

The filtrate flows to the P.C.T;

When amino acids, all glucose are selectively reabsorbed; back into blood stream; Many mitochondria provide energy for reabsorption / for active transport /against a conc gradient; The filtrate flows into loop of Henle moves by osmosis into the blood capillaries; Nacl is actively pumped from ascending arm into blood capillaries;

The filtrate flows into P.C.T; water is reabsorbed; salts reabsorbed; from D.C.T; The filtrate flows into collecting duct; where more water is reabsorbed; ADH influences the amount of water reabs;

The filtrate from collecting duct now referred to as urine / acc. Contents of urine e.g. excess salts, excess water, wastes products / is emplied into ureter into bladder; and out of the body through urethra.

20 marks


Broad /wide lamina; increase S.A for absorption of co2 ; light;

Thin /flat; reduce distance for faster absorption of light;

Transparent cutide; easy penetration of light;

Transparent cutide; for passage of light to palisade cells;

Palisade cells numerous chloroplasts; to trap light;

Spongy mesophyll cells with air spaces; for diffusion of gases;

Vascular bundles; xylem to transport water and mineral salts; phloem to transport

Manufactured food; Guard cells; enclose stomata; for gaseous exchange;

Intercellular spaces; for storage of air / gaseous exchange;

20 marks

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