Answer:
The answer is A.
Explanation:
B) Nucleotides and amino acids can act as extracellular signal molecules:
ATP is made of adenosine (a type of nucleotide) and used in cell signalling called "purigenic signalling" and amino acids are also used as signal molecules.
C) Some signal molecules are transmembrane proteins:
Transmembrane acts as receptors for smaller signal molecules so this can also be accepted as true.
D) Some signal molecules can bind directly to intracellular proteins that bind DNA and regulate gene transcription:
That is also true, some of the hormones can cross lipid membrane of the cells and bind directly to the intracellular (inside-of-a-cell) proteins.
Lastly; dissolved gasses such as nitric oxide can activate proteins such as guanylyl cyclase so this choice is <u>false</u>.
Answer:
a)Difference in physical state observed:
The difference between the two carrots is that the carrot in the plain water appears bigger or slightly swollen while the carrot in the salt water appears smaller and has shrank in length and slightly in width.
b)Process involved that has caused the changes:
The process that has taken place is osmosis.
c)Why has the process occured:
The process occurs due to the semi-permeable membrane of the cells of carrots that allow water either in or out of the cells.
In the plain water, the process that takes place is endosmosis where the cells of the carrot draw in water and hence the carrot increases in mass. The carrot in the salt water, on the other hand, experiences exosmosis, where water is drawn from the carrot's cells and the carrot becomes dehydrated and shrinks in length and width.
d) Beaker 1 : Water
Beaker 2 : Sugar Solution
e) example of endosmosis is absorption of capillary water from the soil by the root.
another example of endosmosis is is entrance of water in the xylem vessel from the soil by the root.
A tissue.
Then a group of tissues that work together is an organ.
The a group of organs is an organ system.
A group of organ systems is and organism.