Correct Answer: C. it is not flexible

Correct Answer: B. light bones

Correct Answer: D. colloid

Explanation

(a) Definition of natural pastures: Pasture is a piece of land on which forage crops/grasses/mixture of grasses and legumes grow (b) Features of natural pastures: (1) Ability to regenerate easily. (2) Growth may be enhanced by burning. (3) Soils are low in nutrients. (4) Contain obnoxious grasses and legumes. (5) Grasses and legumes are poor in quality. (6) Can withstand trampling by ruminants. (7) Forage crops are resistant to drought.

(c) Calculation: (i) Area of land = πr² = 3.142 x 200m x 200m = 125,680m²

Spacing = 1m x 50cm = 1m x 0.5m = 0.5m² Plant population of stylosanthes gracilis

= Area of land (m²) = 125,680m²

spacing (m²) 0.5m² = 251,360 stands

(ii) Expected plant population: Germination:% = 75

i.e = 75 x 251,360/100

Expected plant population = 188,520 Stands of stylosanthes gracilis

OR Area of land = πr² = 22/7 x 200m x 200m = 125,714.28m²

Spacing = 1m x 50cm = 1m x 0.5m = 0.5m²

Plant population = Area of land (m)/spacing (m) = 125,714.28m²/ 0.5m²

= 251,428.56 stands Approx. = 251,429 stands

Expected plant population: Germination % = 75 = 75 x 251,429/100 = 188,572 stands of stylosanthes gracilis

(iii) Importance of stylosanthes gracilis in agricultural production: (1) Fixation of nitrogen from the atmosphere into the soil. (2) Feed for ruminants. (3) Green manure/fallow crop. (4) Checks soil erosion. (5) Improves soil structure.

Correct Answer: A. overdraft

Correct Answer: A. Metallic pond

Correct Answer: C. A population of feral cats begins to hunt the mice in a neighborhood. Mice that are very small are unable to run fast enough to escape the cats, whereas mice that are very large are unable to fit in small nooks and crannies to hide from the cats.

Explanation

Stabilizing selection is a type of natural selection in which the extremes of phenotype are selected against. In other words, individuals with traits on either end of the phenotypic spectrum are more likely to die, or less likely to produce offspring, than those in the middle of the spectrum. This selection against both extremes favors individuals with an intermediate phenotype, and therefore reduces the diversity of the population. The only scenario in which the intermediate phenotype is selected for is the situation describing the cats and the mice. The smallest mice and the largest mice are both eaten by the cats, but medium-sized mice can both run fast enough to escape the cats and fit in the nooks and crannies, making them more evolutionarily fit for survival in this particular situation. The scenario describing rattlesnakes presents an example of directional selection. Smaller rattlesnakes benefit from being able to fit into burrows. Based on this information alone, smaller rattlesnakes may have more offspring than larger rattlesnakes, and the rattlesnake population may eventually select for a smaller body size. The scenario describing elk and antler size is also an example of directional selection. Male elk that have larger antlers are more likely to have more offspring, so the average antler size of the male elk in the population is likely to increase over time. In the example describing hawks, the largest and smallest hawks each benefit from their body sizes, but medium-sized hawks do not. In this situation, disruptive selection is likely to take place, dividing the population over time into two predominant phenotypes. Given enough time, the hawk population might eventually split into two distinct species, one larger and one smaller. The situation describing the moths being blown to an island in a storm describes a founder event, not any type of selection. We don't know anything about the makeup of the population of moths, so we can't say that any particular type of selection is taking place.

Explanation

(a) Production possibility curve may be defined as a diagram or graph showing the possible combinations of two commodities that can be produced given a particular amount of resources and level of technology in an economy, within a given period of time.

(b)

P - Resources are fully utilized

U - Resources are under utilized

X - Production is not feasible

(c) (i) An increase in the supply of productive resources e.g. factor inputs, money, time etc.

(ii) Technical progress: improvement in technology through research and development.

(iii) When productive resources are reallocated to the production of the capital goods as against consumer goods.

(iv) Introduction of new ideas or methods.

(v) Human capital development through training and retraining.

(d) The production possibility curve has a negative slope because it illustrates that there is opportunity cost involved in the production of more of one of the commodities.

(a) Production possibility curve may be defined as a diagram or graph showing the possible combinations of two commodities that can be produced given a particular amount of resources and level of technology in an economy, within a given period of time.

(b)

P - Resources are fully utilized

U - Resources are under utilized

X - Production is not feasible

(c) (i) An increase in the supply of productive resources e.g. factor inputs, money, time etc.

(ii) Technical progress: improvement in technology through research and development.

(iii) When productive resources are reallocated to the production of the capital goods as against consumer goods.

(iv) Introduction of new ideas or methods.

(v) Human capital development through training and retraining.

(d) The production possibility curve has a negative slope because it illustrates that there is opportunity cost involved in the production of more of one of the commodities.

Correct Answer: B. 40√3m /3

Explanation

\(\tan 30 = \frac{x}{40}\)

\(x = 40 \tan 30 = \frac{40}{\sqrt{3}}\)

= \(\frac{40\sqrt{3}}{3} m\)

Correct Answer: D. trypanosomiasis