I’d say B is the best choice
Hope this helps
-AaronWiseIsBae
<span>T he type of selection that favored progressively larger brain size in human evolution is
</span>directional selection. Directional selection is a type of natural selection (besides stabilizing selection, disruptive selection, kin selection,..)<span> in which an extreme phenotype is favored over other phenotypes. Because progressively larger brain size is an extreme phenotype this is a directional selection.</span>
Answer:
The correct option is B) The homologous structures are evidence of descent with modification from a common ancestor.
Explanation:
Homologous structures can be defined as similarities between organs or skeletal of organisms which suggest that they might have a common ancestor in the past. Homologous structures will have alike structures although they may be present in animals of different texa.
For example, The front legs of a frog, which is an amphibian is similar to alligator which is a reptile. This common structure show that they have homologous structures and hence might have had a common ancestor in the past.
Answer:
The miRNAs act as post-transcriptional silencers, as they are similar to specific mRNAs and regulate their stability and translation. They are small endogenous non-coding ribonucleic acid (RNA) molecules, with about 22 nucleotides, which act as regulators of gene expression in plants and animals, at the post-transcriptional level through the cleavage of a target messenger RNA (mRNA) or repression of translation.
In general, most miRNA genes are transcribed by RNA polymerase II in the nucleus in primary miRNAs (pri-miRNAs). Individually, a pri-miRNA can produce a single miRNA or contain groups of two or more miRNAs that are processed from a common primary transcript. These long pri-miRNA are cleaved by a complex comprising the double-stranded RNAse III enzyme (DROSHA) and its essential cofactor, the binding protein DGCR8 (DiGeorge Syndrome Critical Region 8 protein) in mammals. DROSHA contains two domains of RNAse III, each of which cleaves a strand of the RNA resulting in the precursor microRNA (pre-miRNA) with about 70 base pairs, which contains a double-stranded stretch and a single-stranded loop, forming a structure in clamp. The pre-miRNA is exported to the cytoplasm by the protein exportin-5 (XPO-5), where it is cleaved by DICER1, an RNAse III that assesses the 3 'and 5' ends of the pre-miRNA, generating a mature miRNA with about 22 nucleotides. The processing of pre-miRNA by Dicer promotes the unfolding of the RNA duplex in the form of a clamp. The position in the formation of the clamp can also influence the choice of tape.
Explanation:
