Answer: they are not related
Explanation: two different catigories
B. Crystalline structure
C. Types of chemical elements
And
D. Amounts of chemical elements
A dichotomous key helps you identify unknown specimens based on their traits because there are only two options available per trait. Selecting one from the two options (usually contrasting characteristics) from each step leads to smaller and smaller groups until the option is reduced to single and unique trait of an organism.
Considering you need to identify an organism. So, on the top of they key is animal with options: (a) with red blood cells and (b) no red blood cells. The option you will select is no red blood cells and under option b, you’re given two choices again: (a) hard bodies and (b) soft bodies. You’ll select soft bodies, then two options again are given: (a) with shell and (b) without shell. The option you’ll select would be without shell, and so on.
Answer:
1.) The two gametes found in humans are the sperm and the ova.
2.) Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).
3.) Because the alleles that the mother and the father carry are mixed together in the offspring.
4.) Because it only introduces genetic variation into the population if a random mutation in the organism's DNA is passed on to the offspring.
Please this is all I can answer