Each sieve tube element is normally associated with one or more nucleated companion cells, to which they are connected by plasnodesmata (channels between the cells). Each companion cell is derived from the same mother cell as its associated sieve tube member. Sieve tube members have no cell nucleus, ribosomes, or vacues. Thus, they depend on companion cells to provide proteins, ATP, and signalling molecules
The role of xylem is to transport water and some nutrients from roots to shoots and leaves.
Answer: Exergonic reaction; Endergonic reaction
In coupled reactions, the energy released by an exergonic reaction is used to drive an endergonic reaction. ATP breakdown is often coupled to cellular reactions that require an input of energy.
Explanation:
Cellular reactions include Exergonic and endergonic reactions. An exergonic reaction is one that occurs spontaneously and brings about the release of energy (in form of ATP). On the other hand, an endergonic reaction proceeds only with the input of energy.
Thus, exergonic reactions are usually coupled to endergonic reactions
Answer:
C. Enhancer
Explanation:
The enhancer is a regulatory DNA sequence that might be located thousands of nucleotide away from the transcription start site of a gene.
