4. only about 10 percent of the energy in an organism is passed on to the next level of a food chain. look at this food chain: grass → rabbit → hawk what percentage of the energy stored by the grass is passed on to the hawk?

The correct answer is - 1%.

The grass is a plant, thus it is a producer. It produces food for itself through the process of photosynthesis. The grass though is a food source for the rabbit. From the initial 100% energy from the grass, the rabbit manages to get only 10% of it, thus the rabbit will get just one tenth of the total energy of the grass. The hawk is predator, on the top of the food chain, and the rabbit is its prey. The rabbit only got 10% of the energy from the grass, and the hawk will only 10% of those 10% that the rabbit got. In this way, the hawk will get only about 1% of the initial 100% of energy that the grass had.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.