I believe the correct answer is B. Nephridia are excretory organs. They are organs found in invertebrate animals that are present in pairs and are responsible for performing functions that are similar to the kidney of a vertebrate. They excrete wastes from metabolic processes.
Answer:
The cell membranes controls what goes in and out by having protein channels that perform their role accordingly sometimes like funnels and like a pump in different cases.
When a channel open in the plasma membrane it allows molecule to pass through, in this case there is no requirement for energy so it is a passive transport.
Gases and food particles broke down in water must be assimilated and waste or harmful substance and molecules must be remove. For most cells, this type of selective transport of all materials all through the cell must happen through the plasma membrane.
Answer: 20 amino acids
Explanation: The 20 amino acids that are found within proteins convey a vast array of chemical versatility. The precise amino acid content, and the sequence of those amino acids, of a specific protein, is determined by the sequence of the bases in the gene that encodes that protein.
The transmission of an impulse is made possible first by electric signals propagating within a neuron. Then, at the end of the axon called a synapse, chemical substances called neurotransmitters get released to transmit the message. These neurotransmitters then attach to chemical receptors in the following neuron.
The addition of acetyl groups to histones is associated with chromatin condensation and and higher levels of gene expression
