Hi
It is true that on the Galapagos islands Darwin observed tortoises with a dome and saddle shaped shells, you can see both in attached image.
Darwin observed that Galapagos Tortoises had the shells with different shapes depending on the Island they live, For example: The tortoises with saddle shaped shells were able to reach up to eat leaves of plants while the tortoises with dome shaped shells would not reach up and they would eat food from on ground sources. This made him think that the differences in tortoise shell is also a strong evidence that indicates that how tortoises have adapted themselves to better get their food as per the available resources and how they have evolved from same ancestral specie into two different species. This point also helped him in proposing the theory of evolution by natural selection.
Hope it helps!
Here, given-
homozygous alleles 'a' have a frequency of 0.3.
Also the alleles are in equilibrium in a Hardy-Weinberg population. The frequency of individuals that are homozygous for this allele are= 0.49.
The Hardy-Weinberg equilibrium can be defined as the principle which states that the variation in the genetic makeup of a population remains constant and unchanged till there are no external interferences, influencing the population.
Calculation-

Then to find the frequency of the individuals homozygous for this allele the following formula needs to be used-


Thus, the individuals homozygous for the allele can be calculated by 
Learn more about the Hardy-Weinberg equilibrium here-
brainly.com/question/16823644
#SPJ4
The answer is letter C. The distribution of oak trees in an
area.
Population Ecologist would often measure the number
distribution and density of the area. Trees are often measured by plots or by
hectares. This is to know how many trees are situated in that
area.
Answer:
the questions are asking you like what is the carrying capacity for the rabbits and etc.So you take the information from the graph and answer the questions with the information that it is giving you from the graph. I hope this answers your question.