um/Small intestine;

b) B – Aorta ;

F – Venacava ; c)

E ................................................................................ D

- More urea...........................................................- Less urea;

- Less glucose...................................................... - More glucose;

- Less amino acids ............................................. - More amino acids;

- Less oxygeN................................................ - More oxygen;

- More Carbon (IV) oxide ...................................... - Less Carbon (IV) Oxide; Any 3 comparison at 3mrks

d) – Contains bile salts which emulsifies/breaks down fats into (small) droplets; increasing their surface area for action by lipase enzymes; - Neutralizes acidic chyme; (from stomach) - Provides a suitable alkaline P.H; (for the Pancreatic enzymes) (Any 2 at 2mrks) total mks 8

a) S – cuticle;√ ½

X – Palisade cells/Palisade mesophyll layers;√ ½

Y – Spongy mesophyl layers;√ ½

V – Intercellular air space;√ ½
b) V –Stores air temporarily to allow gaseous exchange;

W – Affects opening and closing of the stomata;
c) X – Contains numerous chloroplasts; that form chlorophyll for trapping sunlight; (for photosynthesis)

Y – Loosely packed cells; to allow air spaces for gaseous exchange;

b) Capture and recapture method;

c) i) Sweep net

ii) Nail vanish/indelible ink;
d) - No migration/No movement into and out of the study area;

- There is even distribution of the grasshoppers in the study area;

- There is random distribution of the grasshoppers after the first capture;

- No birth or deaths of grasshoppers during the field study;

e) i) Arthropoda;

ii) Insecta

Reject spelling Arthropod insect. (total 8mks

a) K – White matter;

N – Grey matter;

b) Receptor cells/Nerve endings; Perceive stimuli which are then transmitted as impulses; through the sensory neurone/ L to the relay/intermediate neurone/M; through the synapse to the motor neurone /P; through another synapse to the target organ/gland; (for appropriate response

c)

a) See graph paper

b) i) 2.75g ± 0.5; ii) 39.5g ± 0.5;

c) i)Absorption of water hence rapid increase in mass;

ii) Decrease in dry mass; food stored is oxide/used in respiration to provide energy needed for germination;

d) Photosynthesis occurs; Plumule and foliage leaves are developed; e) To give an average; reduces error in measurement/for accuracy.

f) i) embryo maturity; germination inhibitors; lack of hormones; lack of enzymes; impermeable seed coat. Any @ 1 mark.

ii) water/moisture; oxygen; warmth any 1 @ 1mark.

g) Thin cell walls; dense cytoplasm; no vacuoles. Any @ 1mark

Evidence of organic evolution in life forms

– Fossil record (palaentology); - Fossils are remains of organisms that existed long time ago that have been preserved in plant resins and sedimentary rocks

; - These remains include bones, artfoets and teeth, cellulose cell walls in plants;

- Fossils are important because:-

i. They show an evidence of the type of organisms that existed long time ago

ii. They show gradual change from one form to another over long periods of time. iii. They show evolutionary relationship between organisms. iv. Fossils have been used to construct evolutionary history of organism’s like human beings, horse etc. (6 max 4)
Comparative anatomy;
- It involves comparison of the internal structures of various organisms. - Those organisms with similar structures are believed to share a common origin. The structure can be grouped into;

i. Homologous structures – these are structures with common embryonic origin but modified within the course of evolution to perform different functions due to adaptation of the organisms to different habitats leading to divergent evolution or adaptive radiation ;examples pentadactyl limbs in vertebrates. Beaks in birds.

ii. Analogous structures; – these are structures with different embryonic origin but have been modified within the course of evolution to perform similar functions due to adaptation and exploitation of the same ecological niche. This type of evolution is called convergent evolution; examples:- wings in birds and wings in insects – Those of birds originate from endoskeleton while those of insects from exoskeleton but they perform same functions of flight. Eye in human being and that of Octopus.

iii. Vestigial organ structures – reduced in size and have become functionless in course of evolution but were functional in ancestral forms e.g. reduced wings in Kiwi bird, Appendix, Coccyx in human beings. (12 max 4)

Comparative embryology;
- Embryology is the study of formation and development of an embryo;

- Embryos of different vertebrate group have been found to have similar morphological features during their early stages of development;

- This suggests a common ancestry;

- The closer the resemblance between embryos in early stages the closer the phylogenetic relationship between organisms; (4 max 2)
Geographical distribution (continental drift);
- It is believed that long time ago all the continents formed one large land mass (single mass)

- The mass later broke and the pieces moved away from each other; forming present day continents in a process called continental drift;

- Closely related organisms were separated and isolated from one another ;leading to evolution and subsequent different species; - Different species of organisms inhabit different continents;

- Thus although certain climatic conditions are similar in the same latitudes of different continents, their flora and fauna are not identical. Examples:- Monkeys with long tails live in Amazon forest in South America while in African forests there are monkeys with short tails.

- Australia drifted before evolution of placental mammals hence presence of marsupials. - Isolated oceanic islands evolved their own characteristic plants and animals e.g. Galapagos Islands has both giant Iguana lizards which are terrestrial and marine.(9 max 5)
Comparative serology;
- Analysis of blood proteins and the antigens show phylogenetic relationship - Species more phylogenetically related contain more similar blood proteins. - The amount of immunological reaction that form a precipitate can be used to used to show relationship between organisms. - The greater the amount of precipitate the closer the phylogenetic relation relationship between the animals. (5 max 2)
Cell biology;
- Cells of all organisms show basic similarities in their structure and function - All these cells contain cell membranes, ribosomes, and Golgi bodies and mitochondria they also have biological chemicals in common e.g. ATP and DNA.

- This strongly indicates that all cell types have a common ancestral origin.

- There are also some differences between plant and animal cells e.g. plant cells contain cellulose cell wall, cell sap, chloroplast, starch, chlorophyll all these features are absent in animal cells.

- In animals blood pigments are of universal occurrence e.g. haemoglobin widely in vertebrate and invertebrate; haemoglycnin in annelids. - These differences in plants and animals indicate that from the common ancestral stock plants and animals separated and evolved along different lines.(9 max

Gaseous exchange takes place in a spongy mesophyl; During the day air diffuses into large air spaces of spongy mesophyll; through stomata; the Carbon (IV) Oxide in the air diffuses into Photosynthetic cells; in solution form; during photosynthesis Carbon (iv) Oxide is used while oxygen is produced (some of the) is used in respiration (while the rest of) oxygen;diffuses out of the leaf;through stomata; during the night ;air diffuses into the air spaces (of spongy mesophyll); the air dissolves into film of moisture the oxygen in the air diffuses into cells and is used in respiration during which carbon (iv) oxide is produced, the Carbon (iv) Oxide/oxygen diffuses out of the leaf ;through stomata; due to concentration/diffusion gradient; at night Carbon (iv) Oxide accumulates in the leaf since photosynthesis does not take place, some gaseous exchange also takes place through cuticle;Gaseous exchange takes place through epidermis (of young leaves and stems); epidermis of the root carries out gaseous exchange with air in the soil, some plants have pneumatophores/breathing roots; (through which gaseous exchange occurs) gaseous exchange occurs through lenticel√ (found in older stems); the cork cells out a lenticel are loosely packed gaseous exchange takes place between cork and atmosphere within the loosely packed; cells; (25 marks; a maximum of 20mrks)