Answer:
Question 1
D
Question 2
C
Question 3
D
Explanation:
1. An ecosystem is MOST likely to return to its original condition after Tall prairie grass burns after being struck by lightning.
Here is a research paper in which they explained how this happened. (Komarek, E. V. (1971). Lightning and fire ecology in Africa. In Tall Timbers Fire Ecology Conference (Vol. 11, pp. 473-509).)
2. In some national parks, controlled fires are maintained by firefighters. The major reasons for using controlled burns to maintain certain ecosystems is to give nonnative plants a chance to colonize the region.
A recent article provided the insight of this situation (Xanthopoulos, G., Delogu, G. M., Leone, V., Correia, F. J., & Magalhães, C. G. (2020). Firefighting approaches and extreme wildfires. In Extreme Wildfire Events and Disasters (pp. 117-132). Elsevier.)
3. One reason for the change in the Galápagos ecosystem has been the introduction of species that were not on the island before, such as donkeys, goats, cats, dogs, and insects. The introduction of nonnative species MOST likely disrupt the balance of life on the islands due to greater competition for limited food sources.
Scientist said that food competition is actually a struggle to survive in any ecosystem here is the reference paper (Eckhardt, R. C. (1972). Introduced plants and animals in the Galapagos Islands. Bioscience, 22(10), 585-590.)
Answer:
A. Molecular changes such as extracellular signals on extracellular ligands can result in quick changes in cell behaviour. One example is insulin. Upon insulin binding on the receptor on the cell membrane, the cell release GLUT4 transporters (for muscle cells) to increase uptake of glucose.
B. Slow changes in cell behaviour can be observed for other lipophilic hormones or intracellular receptors such as glucocoortoid or estrogen which reacts with receptors in the cells.
C. Insulin is required to maintain a constant blood glucose level and hence levels of insulin has to be mediated in correspondence to the blood glucose levels. Fast acting signalling is thus required for homeostasis of blood glucose levels. Where for such lipophilic hormones such as steriods, glucocortoid, these hormones tend to have a longer lasting effect and hence results in a slow change.
First one is A
Second one is B
Hope this helps !
Now it is clear that genes are what carry our traits through generations and that genes are made of deoxyribonucleic acid (DNA). But genes themselves don't do the actual work. Rather, they serve as instruction books for making functional molecules such as ribonucleic acid (RNA) and proteins, which perform the chemical reactions in our bodies.Proteins do many other things, too. They provide the body's main building materials, forming the cell's architecture and structural components. But one thing proteins can't do is make copies of themselves. When a cell needs more proteins, it uses the manufacturing instructions coded in DNA.The DNA code of a gene—the sequence of its individual DNA building blocks, labeled A (adenine), T (thymine), C (cytosine) and G (guanine) and collectively called nucleotides— spells out the exact order of a protein's building blocks, amino acids.
Occasionally, there is a kind of typographical error in a gene's DNA sequence. This mistake— which can be a change, gap or duplication—is called a mutation.
