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BIOLOGY-OBJ.

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BIOLOGY ANSWERS 

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)

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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. 

 

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6ai)

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.

(3a)

TABULATE

(i) Disease: Cholera

Causative organism: Bacterium (vibro cholerae)

Vector: Housefly

Control: Keeping environment clean

(ii) Disease: Sleeping sickness

Causative organism: Trypanosome

Vector: tse-tse fly

Control: use of antiseptic

(iii) Disease: Malaria

Causative organism: Plasmodium (protozoa)

Vector: Female anopheles mosquito

Control: Draining of swamps

(iv) Disease: Ringworm

Causative organism: Trichophyton and microsporum

Vector: None

Control: Keeping of skin clean and dry

(3bi)

Salting is the dusting of farm products with table salt

(3bii)

Irradiation is the drying of some crops or products using the heat from the sun

(3biii)

Smoking is the drying of some farm products over a smoke of a naked fire.

(6ai) 

External Fertilization: This type of fertilization occurs when the sperm from the male animal meets the egg/ovum from the female animal, outside the body of the animal. It is common in pisces and amphibians.

(6aii) 

Internal fertilization: a type of fertilization by which the sperm from the male meets the egg/ovum inside the body of the animal. It is common in mammals and birds.

(6bi) 

(i) Pisces e.g: Tilapia, Croaker, Titus

(ii) Amphibians e.g.: Frogs, Toads, Newts

(6bii) 

Internal fertilization:

(i) Mammals e.g. Man, Rat, Monkeys

(ii) Aves e.g. Parrots,Hawks, Eagles

(6ci)

(i) Malnourished and underdeveloped foetus

(ii) Low supply of oxygen to the foetus due to reduced diffusion

(iii) Leads to the death of foetus and miscarriage of pregnancy

(6cii)

(i) Amnion

(ii) Amniotic fluid

(iii) Umbilical cord

(6d) 

Competition in feeding among organisms for scarce resources leads to the death of weaker members of the species and the reproduction of the stronger members, leading to a dynamic equilibrium that balances the rate of death to the rate of birth.

(6e)

(i) Problem of Wave

(ii) Effects of temperature

(iii) Salinity of the Marine

(iv) Humidity

(6fi) 

Moisture helps in the germination of seeds by helping to activate the metabolic activities needed for germination,  dissolved oxygen content in moisture acts is very beneficial to the biochemical process involved in germination.

(6fii) 

Viable seeds are healthy and contain the organic requirements for a healthy germination, and is most times resistant to harsh weather conditions, and lack of nutrients. 

(6g) 

Light energy is considered a limiting factor in production of food by autotrophs because, photosynthesis which is the main process by which autotrophs produce food cannot take place in the absence of light. The energy from light is solely responsible for the process of photosynthesis.

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Please note: This is last year WAEC 2019 biology obj and theory answers below.

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(1ai)

- Tadpole - Skin 

- Cockroach - trachea 

- Domestic fowl - lungs 

- Talinum - stomata 

- Earthworm - Skin 

- Amoeba - cell membrane 

(1aii)

- Large surface area 

- Thin respiratory surface 

- Moist surface 

- Efficient transport system 

- Permeability

(6ai)

The enormous energy of lightning breaks nitrogen molecules and enables their atoms to combine with oxygen in the air forming nitrogen oxides. These dissolve in rain, forming nitrates, that are carried to the earth.

(6aii)

This organism oxidizes ammonia into nitrite as a metabolic process. Nitrosomonas are useful in bioremediation. They are important in the nitrogen cycle by increasing the availability of nitrogen to plants while limiting carbon dioxide fixation.

(6aiii)

Azotobacter helps to synthesizes some biologically active substances, including some phytohormones such as auxins, thereby stimulating plant growth.

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