Johnny, a Living Environment student, has a homework assignment where he must come up with an real-world analogy for the cell wall. Johnny decides that he will compare the cell wall to a doorman because a doorman only allows certain people into a building, just like a cell wall only lets certain materials into the cell. What error did Johnny make in his analogy?

A.
Instead of cell wall, he should have said cell membrane because it is selectively permeable.
B.
Instead of cell wall, he should have said the nucleus because the nucleus decides what enters and exits the cell.
C.
His analogy between the doorman and the cell wall was correct, but the cell wall doesn't allow any materials pass through into the cell.
D.
Johnny did not make an error.

In a hypothetical breed of dogs, coat color is controlled by two genes. there are six different coat colors in this breed: black, brown, cream, gray, silver, and tan. consider the following crosses. cross 1: black females from a lineage of all black dogs are crossed with brown males from a lineage of all brown dogs. f1 males and females are all black. when f1 are intercrossed, f2 males and females are black or brown. cross 2: black females from a lineage of all black dogs are crossed with tan males from a lineage where all males are tan and all females are cream. f1 males are black, f1 females are gray. when f1 are intercrossed, f2 males and females are black, brown, gray, or tan. cross 3: silver females from a lineage where all females are silver and all males are gray are crossed with brown males from a lineage of all brown dogs. f1 males and females are all gray. when f1 are intercrossed, f2 males are black, brown, gray, or tan, f2 females are cream, gray, silver, or tan. select the correct statements regarding the mode of inheritance of the coat color genes. a) both genes are x-linked. b) both genes are autosomal. c) one of the genes modifies the expression of the other gene. d) each gene has an additive effect on the intensity of coat color. e) each gene independently specifies three colors. f) one of the genes is autosomal, and the other is x-linked.

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine

How does photosynthesis show the conservation of mass and energy?