IGCSE Biology Paper-4: Specimen Questions with Answers 203 - 204 of 279
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Question 203
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Short Answer▾Shows the different types of 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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Short Answer▾Table shows different specialized cells and the average number of mitochondria each cell contains.
| specialized cell type | average number of mitochondria |
| liver cell | 1000 - 2000 |
| red blood cell | 0 |
| sperm cell | 25 - 75 |
| heart muscle cell | 1500 |
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.