Free WAEC Biology Expo 2020

1a) The semicircular canals of the inner ear help you with balance. … This movement of the fluid moves the hairs of the canals, creating nerve impulses that travel up to your brain and let it know that your head is off balance. You don’t fall over because your brain tells your muscles to support you.

1iii) The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; theyare also  referred to as the hammer, anvil, and stirrup, respectively.

1a) The semicircular canals of the inner ear help you with balance. … This movement of the fluid moves the hairs of the canals, creating nerve impulses that travel up to your brain and let it know that your head is off balance. You don’t fall over because your brain tells your muscles to support you.

[ 4ai)

Mendel’s law of independent assortment states that genes do not influence each other with regard to the sorting of alleles into gametes: every possible combination of alleles for every gene is equally likely to occur. The independent assortment of genes can be illustrated by the dihybrid cross: a cross between two true-breeding parents that express different traits for two characteristics. 

 *… solving✍🏽*

External fertilization is a mode of reproduction in which a male organism’s sperm fertilizes a female organism’s egg outside of the female’s body. … Invertebrates utilizing external fertilization are mostly benthic, sessile, or both, including animals such as coral, sea anemones, and tube-dwelling polychaetes

6aii) Internal fertilization occurs most often in land-based animals, although some aquatic animals also use this method. In ovoviparity, fertilized eggs are retained in the female, but the embryo obtains its nourishment from the egg’s yolk; the young are fully developed when they are hatched.

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1a) The semicircular canals of the inner ear help you with balance. … This movement of the fluid moves the hairs of the canals, creating nerve impulses that travel up to your brain and let it know that your head is off balance. You don’t fall over because your brain tells your muscles to support you.

1b) check images 

1bii) The middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes. The ossicles were given their Latin names for their distinctive shapes; theyare also  referred to as the hammer, anvil, and stirrup, respectively.

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2a) This is a disease caused by the lack of an element in the diet, usually a particular vitamin or mineral

2aii)Lack of  Calcium causes- Osteoporosis. Rickets. Tetany.

Lack of Iodine deficiency- Goiter.

Lack of Selenium deficiency. Keshan disease.

Lack of Iron deficiency. Iron deficiency anemia.

Lack of Zinc- Growth retardation.

 Lack of Thiamine (Vitamin B1) -Beriberi.

Lack of Niacin (Vitamin B3)-Pellagra.

Lack of Vitamin C- Scurvy.

(Choose any 5)

Mendel’s law of independent assortment states that genes do not influence each other with regard to the sorting of alleles into gametes: every possible combination of alleles for every gene is equally likely to occur. The independent assortment of genes can be illustrated by the dihybrid cross: a cross between two true-breeding parents that express different traits for two characteristics.

 i)* This is a physical test:

-A chemical test for starch is to add iodine solution (yellow/brown) and look for a colour change. 

-In the presence of starch, iodine turns a blue/black colour.

 -It is possible to distinguish starch from glucose (and other carbohydrates) using this iodine solution test.

2bii)- Benedict’s solution is used to test for simple sugars, such as glucose. 

-It is a clear blue solution of sodiumand copper salts. 

-In the presence of simple sugars, the blue solution changes color to green, yellow, and brick-red, depending

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