MRNA can leave the nucleus while DNA can not
Answer:
1. e. Hybrid performance
2. d. Zygote death
3. a. Gametic isolation
4. f. Ecological isolation
5. g. Behavioral isolation
Explanation:
Hybrid performance is a postzygotic isolation mechanism associated with the ability to produce hybrid offspring, which are adaptively less fit than their progenitors (for example, in this case, hydric stress is a limiting factor for the viability of the hybrids). Zygote death is another postzygotic barrier where the zygote parents' genes fight one another and thus impair the development of the hybrid zygote, causing its death. Gametic isolation is a prezygotic isolation mechanism associated with the incompatibility between female and male gametes (i.e., egg and sperm in animals), which join to form a viable zygote. Ecological isolation, also known as habitat isolation, is a reproductive prezygotic barrier caused by the separation of organisms because they live in different areas or have different ecological/ environmental requirements. Finally, behavioral is another prezygotic barrier where closely related species have different mating rituals. Behavioral isolation is a common practice in many species of invertebrates (such as, for example, arachnids).
The answer would be between b and d but i would go with d
Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
