Out of the choices given, the following bacterial cells that would be best able to survive an attack by an antibiotic is; A bacterial cell that has a cell membrane made of ester-linked fatty acids. The correct answer is B.
Answer:
b. A deep, narrow river divides a population of hummingbirds.
Explanation:
Hummingbirds can fly across the river. The deep and narrow river can not separate a population of hummingbirds into two patches since hummingbirds from one side of the river can fly and reach to the other side of the river.
Without any geographical isolation, hummingbirds can continue to interbreed among themselves. The continued interbreeding would not allow their reproductive isolation and thereby would prevent the allopatric speciation.
Carrier proteins pick up specific molecules and take them through the cell membrane against the concentration gradient. Examples of active transport include: uptake of glucose by epithelial cells in the villi of the small intestine. uptake of ions from soil water by root hair cells in plants.
Answer:
c, disruptive selection
Explanation:
Disruptive selection is a term used to describe population genetic changes that simultaneously favor individuals at both ends of the distribution. When disruptive selection operates, individuals at the extremes contribute more offspring than those with intermediate characteristics, producing two peaks in the distribution on a graph.
In the excerpt shown in the question, long-gill-striped and gill-striped fish were favored by the selection process than intermediate-length striped fish. For this reason we can conclude that a disruptive selection was taking place.
