Answer:
The correct answer is beginning of cell mitosis.
Explanation:
Cyclins are cell cycle regulatory protein which regulates the catalytic activity of cyclin dependent protein kinase or CDK.From the name cyclin dependent protein kinase it can be concluded that CDK helps in the phosphorylation of key proteins of cell cycle.
The combination of cyclin with CDK helps in the progression of cell from one phase to another.
Such as cyclin A CDK 2 helps also called G1 cyclin CDK helps in progression of cell from G1 to S phase whereas Cyclin B CDK 1 or M cyclin CDK helps in beginning of mitosis phase or M phase of the regulated cell.
Answer:
a. they can fix carbon at the lower CO2 concentrations that develop when the stomata are closed
Explanation:
C4 plants are those that have the capacity to fix CO2 even when a tiny concentration of it is available.
Desert condition is characterized by dryness and strong heat with both condition capable of creating water stress in plant as a result of evapotranspiration. In order to reduce evapotranspiration rate, desert plants (most C4 plants) close their stomata during the day.
<em>Stomata closure limit the diffusion of CO2 into desert plants and the small concentration of CO2 that results is utilized by a special enzyme in the plants.</em>
The correct option is a.
Explanation:
All living organisms need nutrients to survive. While plants can obtain nutrients from their roots and the energy molecules required for cellular function through the process of photosynthesis, animals obtain their nutrients by the consumption of other organisms. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. However, the food consumed consists of protein, fat, and complex carbohydrates. Animals must convert these macromolecules into the simple molecules required for maintaining cellular function. The conversion of the food consumed to the nutrients required is a multistep process involving digestion and absorption. During digestion, food particles are broken down to smaller components, which are later absorbed by the body. This happens by both physical means, such as chewing, and by chemical means.
One of the challenges in human nutrition is maintaining a balance between food intake, storage, and energy expenditure. Taking in more food energy than is used in activity leads to storage of the excess in the form of fat deposits. The rise in obesity and the resulting diseases like type 2 diabetes makes understanding the role of diet and nutrition in maintaining good health all the more important.
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