Answer:
All of these choices are correct.
Explanation:
Cell cycle is the process of growth and division of cell. It comprises of interphase and mitosis. In interphase the cell grows, replicates its genomic content and prepares itself for division. In mitosis the division occurs.
Cell cycle is controlled by a group of kinases called as Cyclin dependent Kinases (CDKs). They act by phosphorylating their substrates. They are of various types like Cdk1, Cdk2, Cdk4 etc. They become active when they bind to a regulatory protein called cyclin. They are also of various types like Cyclin A, Cyclin B, Cyclin C etc. Level of cyclin and corresponding CDK increases and decreases according to the stage of cell cycle. For example in S phase of cell cycle concentration of cyclin A and E shoots up. CDK2 is able to bind to these cyclin molecules and hence it becomes active.
Cell cycle has major checkpoints where the condition of cell is analysed before it proceeds to the next stage of cycle. If any abnormality is detected, repair mechanism is activated or the cell is killed. Checkpoints do not allow cell cycle to proceed in damaged cells.
p53 is a tumor suppressor protein which can halt cell cycle when it detects some abnormality in cell. It usually acts in G1/S checkpoint (before the DNA replication starts in cell) and G2/M checkpoint (before the cell division begins). Hence, all of the above statements are true.
<span>Men can produce sperm throughout their adulthood because their reproductive organs and glands are fully developed. During their childhood and adolescence the glands and organs are not functional for reproductive purposes.</span>
F - information based on opinion is not valid because it has not been proven right
To know where it rightfully belongs to. Variation of certain traits is caused by multiple factors of an individual of the same kind. Depending on their physical appearance, their environment and nature of survival.
Hope this might help.
Answer;
Mendel's work was not well known until many years after Darwin published his theory of evolution
Explanation;
-Mendel's work was ignored because it was not widely distributed, and he didn't make an effort to promote himself. In actual fact, the reasons are more complex.
-Gregor Mendel had the answer to Darwin's problem. Traits were not blended, but inherited whole. And according to Mendel's laws of inheritance, a trait that might disappear in one generation might reappear in the following generation. Modern Neo-Darwinism combines both Darwin's and Mendel's work.
