The brain's suprachiasmatic nucleus regulates the body's circadian rhythms. The suprachiasmatic nucleus is a minute region of the brain located in the hypothalamus above the optic chiasm, the circadian rhythm is the 24-hour cycle of organisms, related to sunlight and temperature.
Answer:
c. a high percentage of very long chain saturated fatty acids
Explanation:
Saturated fatty acids do not have double bonds (they are saturated with hydrogens), so their tails are relatively straight. Unsaturated fatty acids, on the other hand, contain one or more double bonds, which often produces an elbow or bend. (You can see an example of an unsaturated bent tail in the phospholipid structure diagram that appears at the beginning of this article.) Saturated and unsaturated phospholipid fatty acid tails behave differently when the temperature drops:
- At colder temperatures, the straight tails of saturated fatty acids can be tightly bound, producing a dense and quite rigid membrane.
- Phospholipids with unsaturated fatty acid tails cannot bind so closely due to the bent structure of their tails. For this reason, an unsaturated phospholipid membrane remains fluid at lower temperatures than a saturated phospholipid membrane.
Most cell membranes contain a mixture of phospholipids, some with two saturated (straight) tails and others with a saturated tail and an unsaturated (folded) tail. <u>Many organisms — fish, for example — can adapt physiologically to cold environments by changing the proportion of unsaturated fatty acids in their membranes, that is, increasing the proportion of saturated long-chain fatty acids.</u>
In addition to phospholipids, animals have an additional component in their membrane that helps them maintain fluidity. Cholesterol, another type of lipid that is embedded between the membrane phospholipids, helps decrease the effects of temperature on fluidity.
Answer:
The relationship is that the greater the volume of water in the central vacuole, the greater the turgor pressure, due the more or less amount of water stored in the central vacuole.
Explanation:
As a consequence of the presence of a plant cell in a hypotonic extracellular medium, water passes through osmosis inside the cell, through the semipermeable cell membrane.
The central vacuole is a structure present in plant cells, whose main function is the storage of water. The amount of water present within the vacuole can cause this structure to grow larger or contract, which determines the turgor pressure, which is a phenomenon dependent on osmosis and hydrostatic pressure.
A central vacuole dilated by excess of water produces cell dilation which promotes increased turgor pressure and pushes the plasma membrane against the cell wall.
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Turgor pressure control brainly.com/question/5558909
Explanation:
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