9 is letter d and 10 is a
Once an egg is fertilized by a sperm, a zygote is formed. The zygote divides into multiple cells in a process known as cleavage, triggering the beginning of embryonic differentiation. ... Cells in these three layers will give rise to different parts of the organism. The endoderm eventually becomes the gut.Mar 3, 2011
Dendrite; axon; synapse
These are parts of the neuron which is considered as the basic unit of nervous system. The cell responsible for receiving sensory input from the external environment. The stimulus will be transported in an electrical signal via neuronal parts. Axon transmit signal to the other neuron. Dendrites are the receiving part of the neuron. Synapse is the space between each neuron where elctrical impulse is converted into a chemical signal via neurotransmitters.
Answer:
Helper T cells are arguably the most important cells in adaptive immunity, as they are required for almost all adaptive immune responses. They not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.
Explanation:
Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, which are expressed on the surface of antigen-presenting cells (APCs). Once activated, they divide rapidly and secrete cytokines that regulate or assist the immune response.
