IGCSE Biology Paper-4: Specimen Questions with Answers 202 - 204 of 279

Passage

Soon after starting physical activity the concentration of carbon dioxide in the blood increases.

Question 202 (3 of 3 Based on Passage)

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Name the process inside cells that produces carbon dioxide.

Explanation

Aerobic Respiration

It uses oxygen and completely oxidizes the organic food mainly carbohydrate (Sugars) to carbon dioxide and water. It therefore, releases the entire energy available in glucose and release carbon dioxide.

Question 203

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Shows the different types of human teeth.

The Human Teeth

Describe the functions of the canine and molar teeth.

Explanation

Canines: There is one pointed canine in each maxillary of upper jaw and each dentary of lower jaw next to the incisors. They are meant for piercing, tearing and offence and defense. They are single rooted and monocuspid.

Molars: They have more than two roots and 4 - 5 cuspid. They are meant for crushing, grinding, and chewing.

Question 204

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Table shows different specialized cells and the average number of mitochondria each cell contains.

Different Specialized Cells and the Average Number of Mitochondria Each Cell Contains
specialized cell typeaverage number of mitochondria
liver cell1000 - 2000
red blood cell0
sperm cell25 - 75
heart muscle cell1500

Explain the differences between the average numbers of mitochondria in the cells shown in Table.

Explanation

Mitochondria are cell organelles concerned with the process of aerobic respiration. Of all the cells in human body, it՚s the heart muscle cells with about 1,500 mitochondria per cell that contain far more mitochondria than any other organ in human body. The number of mitochondria reflects the energy requirement of a cell. Heart muscle cells have extra-special demand for ATP to keep the heart pumping. The number of the mitochondria varies with the cell type and functional stage.