Telomeres are regions that make up the end of each chromosome. These 5 nucleotide repeats help preserve the integrity of the DNA during replication. However, in each division, the telomeres shrink. Some scientists have seen in this mechanism a biological clock governing the aging of cells. Until now no one has shown a link between the two phenomena.
The size of the telomeres (the number of repetitions) varies from one individual to another at birth. At each replication cycle, the chromosomes shorten. This is because the enzyme responsible for its replication cannot copy the end of the chromosomes. It is estimated that 100 nucleotides decrease the size of telomeres by division in humans. When the telomeres become too short and before the genes are affected, or the chromosomes merge with each other, the cells stop their division and enter into senescence.
A single enzyme is able to extend the telomeres, telomerase. This enzyme is not active in somatic cells. However, there are somatic cells that are immortal, these are the cancer cells. They have lost control of their cell cycle and can divide indefinitely. This ability to multiply without limit is accompanied by the activation of telomerase.
Answer:
c) microevolution
Explanation:
Microevolution is the change in allelic frequencies within a population over time.
If natural selection favored birds with beaks and small bodies, that means that the frequency of that phenotype (beak and small body) increased while the frequency of birds with body and large beaks decreased.
In this example we see that in the Darwin's finches population, the allelic frequencies - reflected in the phenotype - changed over time as a consequence of the drought.
Answer:
L
Explanation:
The details tell us that the substance starts out and its atoms are "close together and cannot slide past one another." This describes a solid: liquids and gases' atoms can move freely, but solids' atoms cannot move. So we know that the substance starts as a solid.
That means the answer must be L or P, because the solid needs to change into something else.
Then the substance gains energy and it can fill its container. Well, this could be either gas or liquid! So it's a good thing that <u>only L is an answer choice,</u> because that means L is correct and the change is from solid -> gas.
The correct answer is temperature.
Temperature is expected to increase due to climate change.
Temperature is the physical quantity cold and hot.
It is the proportional measure of the average of kinetic energy which is of random motions of continued particles, which is in the matter.
It is measured with a thermometer. Most important in all fields of natural science. For example, biology, chemistry, and earth science.
Answer:
abundance and occurrence are linearly related
Explanation:
The core-satellite hypothesis states that several species will be widespread and several species will be scarce. This is based on the assumption or prediction that species habitation is distributed bimodally.
Hence, according to the core-satellite hypothesis, it is believed that "abundance and occurrence are linearly related."
As there is an increase in the level or number of species, the chance of occurrence or seeing their species increases.