​Bio OBJ:

1-10. CBDBEECCBA

11-20. DBABDBBDDE

21-30. BEEDEDACAB

31-40. BAAADBBBEA

41-50. EABDCDAAED

51-60. ABDBACCDBB

Bio Theory:

1ai)

Sexual reproduction:This is a type of reproduction which involves the fussion of male gametes(eg sperm cell) and the female gametes(eg egg cell) to form zygote which later develops to a young offspring

1aii)

-Abstinence

-Birth Control Sponge (Today Sponge)

-Birth Control Vaginal Ring (NuvaRing)

-Birth Control Shot (Depo-Provera)

-Birth Control Implant (Implanon and Nexplanon)

1aiii)

-Mutualism represents a symbiotic relationship where both species involved benefit from the relationship while commensalism represents a symbiotic relationship where only one organism benefits while the other does not benefit from the relationship

-Good examples for mutualism include the relationship between bees and flowers as well as humans and digestive bacteria while Examples for commensalism include hermit crabs using dead gastropods for shelter or millipedes travelling on birds

1b)

i)Hooks and suckers allow it to hold on tightly to the wall of the intestine

ii)Its flat body gives it a large surface area to absorb food

iii)It has no need of a mouth or gut as it absorbs already digested food

1ci) See the diagram.

(1cii)

-Evidences from Palaeontology

2ai)

i) Acidification: This is a method of adding acid to a loe acid food. Acid can be used in food to slow down or prevent the growth of disease or spoilage causing organisms

ii) Drying of Food: Food drying is a method of food preservation in which food is dried (dehydrated or desiccated). Drying inhibits the growth of bacteria, yeasts, and mold through the removal of water.

iii) Home Canning: Home canning is a way to preserve fresh foods in glass jars and then heating the jars to kill the organisms that would create spoilage

iv) Freezing Food: This is a method of preserving food by lowering the temperature to inhibit microorganism growth.

2aii)

i) Vector is an organism that does not cause disease itself but which spreads infection by conveying pathogens from one host to another. Species of mosquito, for example, serve as vectors for the deadly disease Malaria

ii) Refuse can be defined as All nonhazardous solid waste from a community that requires collection and transport to a processing or disposal site

iii) Sewage is a type of waste water that is produced from a community of people. It is characterized by volume or rate of flow, physical condition, chemical and toxic constituents, and its bacteriologic status

2b)

i) Mineral salts from soil

ii) Products of photosynthesis from leaves

2c) See the diagram

5ai)

Respiration is the exchange of oxygen and carbon dioxide between the toad and its environment. Oxygen is taken into the body and carbon dioxide is given off. Every cell of the body consumes oxygen. With the help of oxygen, the assimilated food which is stored within the cells is slowly oxidised.

The result is the liberation of heat energy, and formation of carbon dioxide and water. Thus when glucose is oxidised, one molecule of glucose combines with six molecules of oxygen to form six molecules of carbon dioxide and six molecules of water.

5aii)

1) consideration of the oxygen isotopic records of low latitude temperature variations;

2) discussion of the physical arguments for temperature stability within the tropics;

3) examination of climate model-derived tropical temperatures;

4) examination of model evidence for tropical salinity differences between different time periods in Earth history

5bi)

i. Natality (birth rate):This refers to the rate of given birth to new organisms. This generally (be it plants or animals) leads to increase in population.

ii. Mortality (death rate):This refers to the rates at which organisms die in a habitat. Mortality generally leads to a decrease in population.

iii. Immigration (dispersal):This is the movement of organisms from different habitats into a new habitat. This tends to increase the population of this new area.

Iv. Emigration: This is the movement of organisms out of a habitat due to either scarcity of food or unfavourable conditions or for breeding purposes. This, however, reduces the population of a habitat.

V. Availability of food: The availability of food in a given habitat tends to increase the population of that habitat through rapid rate of reproduction and other organisms coming into feed.

5bii)

i. homozygousis when a cell has two identical copies of a gene. An example ofhomozygousis a cell

ii. heterozygote -is an individual having two different alleles of a particular gene or genes, and so giving rise to varying offspring

iii. parasite- an organism that lives in or on an organism of another species (its host) and benefits by deriving