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Answer

2018 WAEC GCE BIOLOGY ESSAY ()

Use this obj PLS

1-10CBDBDBBBBC
11-20BBCCBADDDC
21-30 DBDCCCBAAA
31-40 CCAACBABBC
41-50 CBCBBBBDAB

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1a

Mammalian Skeleton. Mammals are highly advanced vertebrate animals and have complex skeletons. … The axial skeleton consists of the skull, spinal column and rib cage and the appendicular includes the bones of the arms, legs, hands, feet, pelvis and shoulder.
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1b

i. Exoskeleton eg..
ii. endoskeleton eg. Mammals
iii. Hydrostatic skeleton eg. Soft body animals

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1c)*Functions of mammalian skeleton*

Support:

The skeleton provides the framework which supports the body and maintains its shape.

Movement:

The joints between bones allow movement, some allowing more than others. Movement is powered by skeletal muscles. Muscles, bones and joints allow movement, all coordinated by the nervous system.

Protection:

The skeleton helps to protect the vital organs from being damaged. Ribcage, sternum and spine protect the lungs, heart and major blood vessels; the skull protects the brain; the vertebrae protect the spinal cord.

Blood cell production:

The skeleton is the site of haematopoiesis, the development of blood cells which occurs in the bone marrow.

Storage:

Bone can store many minerals. The bone matrix can store calcium and is used in calcium metabolism. Bone marrow can store iron in ferritin and is involved in iron metabolism.

Attachment:

The skeleton provides many points of attachment fro muscles and tendons. The bones also attach to hold the body together (see support).
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(2a)
Vitamins are group of organic compounds which are essential for normal growth and nutrition and are required in small quantities in the diet because they cannot be synthesized by the body.

(2b)
Vitamin: C
One Function: Healing of wounds
One Deficiency: Scurvy
One Source: Citrus Fruits

Vitamin: D
One Function: Strong bones and teeth
One Deficiency: Rickets
One Source: Eggs

Vitamin: B
One Function: Releases energy from cabohydraes
One Deficiency: Beri-beri
One Source: Yeast

Vitamin: K
One Function: Clotting of blood
One Deficiency: Failure of blood to clot
One Source: Milk

(2c)
(i) Iron: Assists in nitrate and sulfate reduction and energy production within the plant

(ii) Nitrogen: For rapid growth

(iii) Calcium: It is responsible for holding together the cell walls of plants

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2c : Calcium : … It is needed in large amounts by all
plants for the formation of cell walls and cell membranes,

Nitrogen is so vital because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (i.e., photosynthesis)

In plants, iron is involved in the synthesis of chlorophyll, and it is essential for the …. Rice phenolics efflux transporter 2 (PEZ2) plays an important role in solubilizing apoplasmic
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5a. Osmoregulation

Osmoregulation is the active regulation of the osmotic pressure of an organism’s body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism’s water content; that is, it maintains the fluid balance and the concentration of electrolytes (salts in solution) to keep the fluids from becoming too diluted or concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution, the more water tends to move into it. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water.

5B

Designing the Experiment
This stage of the scientific method involves designing the steps that will test and evaluate the hypothesis, manipulating one or more variables to generate analyzable data.

Observation
This is the midpoint of the steps of the scientific method and involves observing and recording the results of the research, gathering the findings into raw data

Analysis
The scope of the research begins to broaden again, as statistical analyses are performed on the data, and it is organized into an understandable form.

Conclusions and Publishing
This stage is where, technically, the hypothesis is stated as proved or disproved.

5c

The atrioventricular node , or AV node is a part of the electrical conduction system of the heart that coordinates the top of the heart. It electrically connects the atria and ventricles.
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