Answer:
You have 20% of adenine. If you have 20% of adenine than you have 20% of thymine, because the amount of adenine and thymine is equal. 20% plus 20% is 40% of adennine and thymine. From 100% DNA bases subtract 40% and you will get 60%. Then divide this by 2 and you will get 30%. 30% of guanine and 30% of cytosine, because their amounts are equal in the DNA stand.
Explanation:
That question, this incomplete. The full question is:
3. Three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. One tree is left outside in normal conditions. The heights of the trees are measured once a week. What are the dependent variables, independent and the controlled variable of this experiment?
Answer:
- Independent variable: different humidity levels
- Dependent variable: the heights of the trees
- controlled variable: the types of trees
Explanation:
An independent variable is one that exerts an influence within the experiment and can be measured, acting on other elements to promote the observation of a result. As the experiment seeks to observe the influence of humidity on the height of the tree, we can say that humidity is the independent variable.
Dependent variable is that which is influenced by the independent variable to generate a result that can be observed, can also be measured. As the experiment wishes to analyze how the height of the trees was affected by the level of humidity, we can say that the height of the trees is the dependent variable.
Controlled variable is that which is present in the experiment in a constant and equal way, cannot be measured. This variable is the type of trees.
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.
