The process of sexual reproduction involves two parents, each contributing one gamete. Gametes are produced
by a process called meiosis, which starts by the duplication of the
chromosomes, followed by two rounds of cell divisions and halving of the
chromosome number. Gametes have half the chromosome number of other
adult
cells of an organism.
A key feature of meiosis is the exchange of chromosome pieces which occurs in the first division of this process, called recombination or
crossing over. Recombination is a very important source of genetic
variation between individuals of sexually reproducing species, and the
driving force for the process of natural selection.
Answer:
A
Explanation:
The correct answer would be that <u>de novo incidences of DiGeorge syndrome occur as a result of errors during maternal or paternal meiosis, creating a new variant.</u>
<em>Since the syndrome has high penetrance, it is highly unlikely that any of the parents would be misidentified or that one of the parents has the variant without symptoms. It is also highly improbable that both parents would be carriers because if they do, they will definitely show some symptoms.</em>
Hence, the most likely explanation is that the variant emerges as a result of errors during maternal or paternal meiosis leading to the formation of a gamete with the variant.
The correct option is A
Answer:
The answer is A.
Explanation:
B) Nucleotides and amino acids can act as extracellular signal molecules:
ATP is made of adenosine (a type of nucleotide) and used in cell signalling called "purigenic signalling" and amino acids are also used as signal molecules.
C) Some signal molecules are transmembrane proteins:
Transmembrane acts as receptors for smaller signal molecules so this can also be accepted as true.
D) Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription:
That is also true, some of the hormones can cross lipid membrane of the cells and bind directly to the intracellular (inside-of-a-cell) proteins.
Lastly; dissolved gasses such as nitric oxide can activate proteins such as guanylyl cyclase so this choice is <u>false</u>.
C) reproduce on it's own!
I think it’s D because less carbon would normally be produced in the absence of sunlight. Also, less energy would be present if no sunlight is there