Answer:
The correct option is <u><em>A. they evolved from land mammals.</em></u>
Explanation:
The process of evolution explains how closely one organism is to another based on their common ancestors. Scientists believe that those organisms which show many similarities in their structures or functions might have evolved from a common ancestor in the past.
As in the above-mentioned question, scientists have observed that cetaceans lack gills and breath air, this is a property of land mammals. The cetaceans have fin bones which are similar to the limb bones. As limb bones are present in land mammals, hence they cetaceans and land mammals might have common ancestors in the past.
Answer:
d. cerebellum.
Explanation:
The cerebellum, which is part of the hindbrain, is a small structure made of a covering of white cortex found under the hemispheres of the cerebral cortex. The cerebellum plays a major role in the control and coordination of all physical movements such as balance, control, etc, that has to deal with smooth and balanced activities of the muscle.
A damage to the cerebellum would most likely lead to impaired motor coordination, staggering, inability to judge distance or when to stop.
Answer:
Due to number of amino acids.
Explanation:
The main differences might be expected in the amino acid composition of X versus Y because the X polypeptide is made up of one smaller unit of amino acid while on the other hand, Y polypeptide is made up of four smaller units of amino acids. The name of X is monomer which means composed of one amino acids while Y exists as a tetramer which means it has four amino acids. So we can conclude that the main difference between X and Y is the presence of number of amino acids.
Answer:
They became closer to each other.
Explanation:
When skeletal muscles contracts the Z lines that are at the end of every sarcomere became closer to each other due to the fact that the I bands that are attached to the Z lines and contains the myosin filaments move closer to each other interacting with the actin filaments and shorten the the H zone that is in the middle of the sarcomere. In other words, It all becomes compact during a contraction.
Answer:
Chromatin helps regulate DNA replication.
Explanation:
Chromatin helps condense DNA strands to smaller units that can be easily managed during DNA replication and gene expression. This also prevents the breakage of the strands and facilitates equal distribution of chromosomes during cell division (during mitosis and meiosis).
