Answer:
- Sister chromatids are not homologous chromosomes.
- Crossing over occurs between non-sister chromatids.
Explanation:
- "<em>Sister chromatids are not homologous chromosomes</em>". IT APPLIES.
- One chromatid is a chromatin strand that got thick after folding. The chromatin strand is the DNI double helix associated with histones. Before cellular division, the chromatin strand generates a copy or clon, so both of the daughter cells can get the same genetic information. These two strands keep joint together by a centromere. The chromosome is conformed by the chromatin strand and its copy, condensated and joint by the centromere. It looks X-shaped. The chromatin strand and its clon are known as sister chromatids, and they are together on the same chromosome. So one chromosome is composed of two chromatids.
- Homologous chromosomes are those that give information for the same trait, but this information is not necessarily the same. For example, both homologous chromosomes might give information for hair color trait, but one of them gives information for brown hair and the other one gives information for black hair.
2. "<em>Crossing over occurs between non-sister chromatids"</em>. IT APPLIES.
- Crossing-over occurs <u>between two homologous chromosomes</u> in the equatorial plane, that makes the daughter cells to be genetically different from the original one.
3. "Sister chromatids are found on two different homologs". IT DOES NOT APPLY.
- The chromatin strand and its clon, known as sister chromatids, are together on the same chromosome. <u>So one chromosome is composed of two chromatids. </u>
4. <em>"A chiasma forms between four molecules of double-stranded DNA on duplicated homologous chromosomes". </em>IT DOES NOT APPLY
- Chiasma is the point where two chromatids interchange genetic information making a place to new genetic material or information that will be inherited to descendants. Chiasma allows the crossing-over between <u>two homologous chromatids</u>, one of each parent.
Answer:
Ii
Explanation:
Because it has one dominant allele <em>(I)</em> and one recessive allele <em>(i)</em>.
Answer:
scientific consensus changed as scientists learned more about organisms.
Explanation:
The classification system for organisms has changed from seven levels to eight level of classification system because scientists learned more about organisms. This new learned information allow scientists to change the existing classification system. When the scientist find new species that may have to change classification systems in order to accommodate them and placed them accurately in the classification system.
Answer:
a. methylation at lysine 9 or 27 of histone H3.
Explanation:
Methylation causes the switching off of genes using steric hinderance to prevent access to DNA.
Homeostasis is <span>the body's tendency to maintain relatively stable internal conditions in spite of greater changes in its external environment. It is a process in which all body cells are involved and through which the body systems stays stable and keeps constant internal environment. Homeostasis enables the body to maintain its balance and stability. </span>
