Define the following terms. Give an example of an organism that is described by each term. a. benthic b. pelagic c. sessile d. mobile e. evisceration f. chitin

(A) Benthic- Benthic refers to the lowest or the bottom zone of the water body such as seas, and oceans. The organisms existing under such extreme pressure conditions are commonly known as benthic organisms. For example, corals and bivalves.

(B) Pelagic- Pelagic refers to the upper top portion of a water body, covering the open sea areas. The organisms existing in this region include dolphins and sharks.

(C) Sessile- Sessile refers to the property where an organism is stationary and cannot move freely from one place to another. These are known as sessile organisms such as coral polyps, Mussels.

(B) Mobile- refers to the property by which an organism can move freely in any direction it wants. For example, fishes, dolphins.

(E) Evisceration- It is a specific type of property where organisms can eject their internal organs in order to protect themselves from predators. for example, Sea cucumbers.

(F) Chitin- Chitin is a hard shell that is present in various organisms, forming its exoskeleton, for defense purposes. For example, arthropods.

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.