The correct answer is: A. The hydrophilic head groups of the lipid molecules are exposed to the outside of the cell and the cytoplasm, which is a water-like environment. The hydrophobic tails form an oily layer inside the membrane that keeps water out of the cell.
Plasma membrane of the cell is arranged in a bilayer of phospholipids. Phospholipids are amphipathic molecules which means that they have both hydrophilic and hydrophobic regions. The hydrophilic heads of phospholipids that are faced outward and hydrophobic layer located in the interior of the bilayer together make a good barrier between the interior and exterior of the cell, so the water and other polar or charged substances cannot easily cross the hydrophobic core of the membrane.
Question: Does geographic distance between salamander populations increase their reproductive isolation? To answer this question, researchers studied populations of the dusky salamander (Desmognathus ochrophaeus) living on different mountain ranges in the southern Appalachian Mountains. The researchers tested the reproductive isolation of pairs of salamander populations by leaving one male and one female together and later checking the females for the presence of sperm. Four mating combinations were tested for each pair of populations (A and B)—two within the same population (female A with male A and female B with male B) and two between populations (female A with male B and female B with male A). The proportion of successful matings for each mating combination was measured. For example, when all the matings of a particular combination were successful, the researchers gave it a value of 1; when none of the matings were successful, they gave it a value of 0. Then the researchers calculated an index of reproductive isolation that ranged from 0 (no isolation) to 2 (full isolation). The reproductive isolation value for two populations is the sum of the proportion of successful matings of each type within populations (AA + BB) minus the sum of the proportion of successful matings of each type between populations (AB + BA).
The table (Figure 1) provides data for the geographic distances and reproductive isolation values for 27 pairs of dusky salamander populations.
Part A - Understanding experimental design
What hypothesis did the researchers test in this study?
Answer:
"Reproductive isolation increases with geographic distance between dusky salamander populations"
Explanation:
The mechanisms of reproductive isolation are a assemblage of evolutionary mechanisms, behaviors and physiological procedures dangerous for speciation. They avert followers of dissimilar types from manufacturing offspring, or confirm that any offspring are germ-free. While in allopatric speciation the reproductive isolation is resolute superficially by the spatial isolation of populations, during sympatric speciation specific groups of persons create distinct mating organizations with self-like persons while distribution the similar home with the rest of the unique inhabitants.
Answer: biotic factors include plants and animals. So, the rainforest animals are more adapted to warmer weather meaning they have less fur and are built for warmer weather. The plants in a rainforest need lots of water to survive as well as carbon dioxide so they have large, wide leaves.
In a Taiga biome, the animals have more fur and adaptations to help them to survive in colder weather. The plants primarily consist of fir and pine trees, which have waxy, needle-like leaves to retain water as well. The trees also dont lose their leaves in the winter.
Explanation:
The process is called digestion
