Answer:
The correct answer will be option-formation of heterochromatin
Explanation:
Methylation of DNA is the epigenetic mechanism which controls the expression of a gene by adding a methyl group to the cytosine bases in eukaryotic DNA.
The methylation of DNA converts the cytosine residues to the 5-methylcytosine catalysed by DNA methyltransferase enzyme. This results in the silencing of the gene and transcription get switched off.
Studies have shown that DNA methylation is involved in the formation and maintenance of the heterochromatin structure which is the condensed form of the chromatin in which transcription is switched off.
Thus, the formation of heterochromatin is the correct answer.
<span>the large population becomes smaller.
also, bottleneck is when a large population quickly shrinks. the effects of genetic drift becomes much stronger.
e.g: seals
alleles can be lost during bottleneck and the number of alleles left can shift dramatically in just a few generations.</span>
Answer:
(a) crossing over: Meiosis I, Recombination
(b) chromatids separate at their centromeres and migrate to opposite poles: Meiosis II, Anaphase II
(c) chromosomes become aligned in pairs at the equator: Meiosis II, Metaphase II
Explanation:
Homologous recombination is a type of genetic recombination that occurs during meiosis (formation of ovum and sperm cells). The paired chromosomes of the male and female parents are aligned so that similar DNA sequences intersect. This crossing over produces an exchange of genetic material, which is an important cause of the genetic variability observed in the offspring.
Meiosis II: Anaphase II. The centromeres separate and the daughter chromatids - now individual chromosomes - move to the opposite poles of the cell. The centromeres separate, and the two chromatids of each chromosome move toward the opposite poles in the spindle.
Meiosis II: Metaphase II. Chromosomes are accommodated in the equatorial plate of metaphase, similar to what happens in mitosis. They are attached to the already fully formed meiotic spindle. Each chromosome is aligned in the equatorial plate of the metaphase, as it happens in mitosis.
The correct answer is option C, that is, physical weathering.
The weathering resulting due to the influences of changing temperatures on a rock, making the rock to split apart is known as physical weathering. There are two main kinds of physical weathering, that is, exfoliation and freeze-thaw.
Physical weathering takes place mainly in the locations, where few plants grow and little formation of soil occurs, like hot deserts and mountain regions. It takes place either via repeated freezing and melting of water or via contraction and expansion of the rocks surface layer, which is baked by the sun.
Answer:
Limiting human use of nitrogen that is in the atmosphere.
Explanation:
