Correct Answer: B. spirogyra

Correct Answer: C. asexually with the same genotype as the parent plant

Correct Answer: D. ll and lV only

Explanation

Pesticides that are sprayed on to fields and used to fumigate soil can give off chemicals called volatile organic compounds, which can react with other chemicals and form a pollutant called ground level ozone.

Sulfur dioxide (SO2) is a gaseous air pollutant composed of sulfur and oxygen. SO2 forms when sulfur-containing fuel such as coal, oil, or diesel is burned.

Correct Answer: D. variation

Correct Answer: D. Rhizopus

Correct Answer: B. lll only

Explanation

(a)(i) Biosphere: Total/whole area, part of the earth/lithosphere/ hydrosphere/water, and atmosphere/air, inhabitable by living things/where life exists.

(ii) Habitat: A place/home; within an environment, where an organism naturally lives/dwells.

(b) Mode of nutrition of named carnivorous plants:

• - Carnivorous plants have green leaves and are able to manufacture their own food carry out photosynthesis.
• They have roots to absorb water and mineral salts from the soil.
• Usually grow in places with little nitrogenous salts.
• Use insects/other small animals as source of Nitrogen.
• They have devices/modified leaves with bright colour/sents/sugary liquids/stcky wet surfaces for attracting and trapping insects.
• Once the insects is trapped, the plant secretes enzymes to kill and digest it.
• The soluble nitrogenous compounds are absorbed/assimilated by the plant.

Name of carnivourous plants: -

• Butterwort/Pinquicula
• Bladderwort/ Utricularia
• Sundew/Drosera
• Venus fly-trap/Dionaea
• Pitcher plants/Nepenthes/Sarracenta.

(c) Importance of fruits and seed dispersal: -

• Prevents overcrowding of plants.
• Prevents undersirable competition for space/light/water and nutrients.
• Prevents diseases from spreading among plant species.
• Results in colonization of new areas with new plants.
• Results in adaptation to adverse/harsh/unsuitable environment.

(d) Soil conservation method: -

• Contour ploughing/ridges are made along the contour of a slopping land/to prevent water running down the hill/slope/and washing away soil.
• Strip cultivation/the land is divided into strips along the contours of the slopes/crops are planted in rows that alternate with the strips planted with cover crops/grasses.
• Terracing/constriction of terraces which create barriers to hinder rapid water flow down the slope.
• Mulching/materials left after weeding or harvest are left to lie on the soil/ protecting the soil against agents of erosion.
• Afforestation/cover cropping/growing grasses, trees and shrubs to cover and protect the soil.
• Crop rotation/growing crops on a piece of land in sequence/season after season to maintain its fertility.
• Storm drains/construction of barriers/to stop free-flow of surface water through farms.
• Application of manure/fertilizer/to stabilize the soil.
• Avoid bush burning.
• Avoid over grazing.

Correct Answer: A. allows for quick regrowth of grasses

Correct Answer: C. in the root nodules

Explanation

(a) Definition of terms:

(i)Elimination: Removal of undigested food; from the body of living organisms.

(ii)Excretion: Removal of waste products of metabolism; from the cells/tissues of an organism; may be toxic if retained in the body.

(iii)Secretion: Production and release of substances; useful to the body; by specialized glands of living organism.

(b) Digestion of boiled fish in the gut of humans:Boiled fish is a source of protein; chewed and swallowed into the stomach; digestion of protein starts from the stomach; stomach secrets gastric juice; containing pepsin, rennin and hydrochloric acid; pepsin in acidic medium acts on the boiled fish and convert it to peptides; peptides move into the duodenum/small intestine; into which pancreatic juice is secreted; undigested protein is acted upon by trypsin in alkaline medium; into peptides/peptones, erepsin finally acts on peptides/peptones in alkaline medium; and converts it into amino acids.

(c) Diagram of villus

Title TL: - Longitudinal section of villus. Size: (8 — 10cm long).

Quality (Q): Clarity of lines. Neatness of labels.

Details: Epithelium layer shown (EL) Conical shape of villus (one cell thick) (CV).

Labels (L): Epithelium layer blood capillary, lacteal, lymphatic vessels, goblet cells, venule, arteriols, cryps of lieberkuhn, cells of paneth, muscularis mucosa.