Answer:
The phloem connects the leaves to the stem and roots of the plants by transporting the sucrose to various parts.
The correct answer is:
Plants close their stomata during times of intense heat or drought in order to prevent water loss and maintain homeostasis.
Explanation:
Guard cells tend to open stomata within the day when there are lots of day and close stomata at night when the sun is not present and photosynthesis is not happening. They will also close stomata if the air is dry or hot, which minimizes water waste indoors evaporation.
Answer:
A mutation may be bad and good depending on the particular environmental conditions
Explanation:
For example, the falciform anemia is a hereditary disease caused by a mutation where the ability to transport oxygen of red blood cells is reduced; however, this genetic disorder is widespread in some African populations because it is a condition that confers resistance to falciparum malaria. In consequence, falciform anemia is a detrimental mutation that may also be beneficial in endemic malaria regions.
Moreover, it is important to note that the higher proportion of non-synonymous substitutions are not subject to selection (only a minor percentage are positively selected) because they are generally localized within non-coding regions, thereby having neutral status.
It is true that telomerase activity declines with old age which explains why cells lose their ability to divide after many replications.
Telomeres are DNA–protein complexes found at the ends of each chromosome they contain repetitive sequences of DNA. Telomeres protect the genome from nucleic bases degradation, unnecessary recombination, repair, and prevent the fusion of chromosomes. Telomeres, therefore, play a vital role in preserving the information in our genome.
Telomeres shorten with every consecutive DNA replication cycle limiting the number of cell divisions a cell can undergo, Telomeres act as a tumor suppressor by halting the replication of cells which contains several mutations after many division cycles.
To learn more about tumor suppressors here
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