Sucrose is transported throughout plants in phloem tissue, as shown in the model. the varying concentrations of water and sucrose allow for the movement of both of these molecules through the plant. which explanation best describes the transport of sucrose in the plant? a) sucrose is moved into the companion cells and sieve tubes against its concentration by active transport. b) sucrose is moved into the companion cells along its concentration gradient by facilitated diffusion and then into the sieve tubes by osmosis. c) sucrose is moved into the companion cells against its concentration via active transport and then into the sieve tubes by facilitated diffusion. d) sucrose is moved into the companion cells along its concentration gradient by facilitated diffusion and then into the sieve tubes by simple diffusion.

A

Explanation:

Sucrose is actively transported AGAINST a concentration gradient into sieve-tube elements. Technically, the sieve-tube elements LACK (have no) NUCLEI but the adjacent companion cells do. Companion cells are CLOSELY ASSOCIATED with sieve tubes and ALSO CARRY OUT ALL THE CELLULAR FUNCTIONS of the sieve tubes as well.

It's C Sucrose is moved into the companion cells against its concentration via active transport and then into the sieve tubes by facilitated diffusion.

Explanation:

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.