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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;
(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);
(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.
(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.
X - Nucleus;
Z - Cilia;
-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;
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
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.
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;