Answer:
8. D
9. A
10. A
11. C
12. D
Explanation:
8. Natural selection works on variation that exists in the genes of organisms. Antelopes who have genetic variation that makes their legs more muscular are at an advantage because they can outrun predators. This increases the chance that they will reach reproductive age, and be able to pass this advantageous trait onto their offspring. Over time, this selection pressure makes the variant more common in a population.
9. Beneficial traits are those that give a selective advantage. This could be one that helps it outrun predators (like above), avoid illness and death, gives it a reproductive advantage (i.e. more attractive to mates), or makes it better able to digest certain foods, for example. The formation of cancer cells would be harmful for an organism, reducing its fitness and perhaps leading to death. The inability to reproduce would mean genetic info is not passed on to the next generation, and stopping the production of an essential protein would likely lead to death. However, resistance to a virus would help an organism avoid illness and death, improving fitness.
10. Genotypes are what organisms inherit from their parents, i.e. the genetic information that is passed on. However, the way in which different alleles interact and are expressed is the phenotype. If we take the above example, natural selection is acting on the phenotype of muscular legs. If an antelope had the muscular leg genotype but for some reason it was not being expressed (maybe another gene is interfering with it), then the antelope would not have a selective advantage, and natural selection could not be act on the trait.
11. A trait that better suits an organism to its environment will be selected for by natural selection. This is because that organism is more likely to survive due to the trait, giving it a selective advantage. Therefore, if a mutation arose making the giraffe more adapted to the environment, it would be positively selected for, and through evolution would become more common.
12. This is an example of selective breeding, which has been happening for generations. Farmers spot desirable traits, and cross horses with these traits in an attempt to enhance the trait or to ensure it is passed on to the next generation. This is not natural selection, because farmers are making it happen artificially. It is not cloning or recombinant DNA, which are terms scientists use for actually manipulating the DNA in the lab.
I found the attached image on the internet related to this question.
The solid arrows represent neuronal communication. The stimulus, the effects, and the flow of information is all done by receptors and synapses that send a signals across the body in order to have effective feedback responses promoting the homeostasis of the organism.
A is the correct answer!
- water can moderate temperature v. well that's why it's used as a cooling agent
- water expands upon freezing (that's why ice floats on water!)
The answer is B.
It describes the relationship between photosynthesis and respiration accurately.
Answer: The most affected would be organs that have QUICKLY dividing cells (like the intestine and hair follicles).
Explanation:
Cancer cells are cells that divides uncontrollably giving rise to a mass of tissue called tumour. They grow faster than a normal cell in an uncoordinated manner, and continues to grow after the initial stimulus has ceased.
Paclitaxel is a drug that is approved for the treatment of cancer affecting different parts of the body. It's a microtubule-stabilizing drug whose mechanism of action is to induce mitotic arrest in the cancer cells.
Paclitaxel in its cause of action not only affect cancer cells but normal cells as well. To justify this statement, as stated earlier, the mechanism of action of paclitaxel is to induce mitotic arrest. Therefore the cells of organs where rapid mitosis occurs would be most affected. Skin cells, hair follicles and the cells lining our intestines (epithelial cells) all have high rates of mitosis as these tissues constantly need to be replaced.
