A physical oceanographer does not study fish therefore your answer is D. Fish
Crops that humans grow have decended from wild plants and are resistant to diseases and pest.
Explanation:
- The science of growing crops is known as agriculture.
- Humans have been developing agriculture since times immemorial.
- They have selected and cultivated crops that gave a better yield and developed new varieties by cross breeding Superior varieties with the inferior ones.
- Usually the cross bred varieties are cultivated and are resistant to pests and diseases.
Answer:
macrophages
Explanation:
Macrophages are a type of immune cells that function as phagocyte. They are produced by white cells called the monocytes. Upon ingestion of bacterial cells, cytotoxic compounds e.g cytokines are produced that digest the bacteria.
The macrophages are activated by the presence of microbes in the blood. They activate antigen T presenting cells to produce cytokines that further destroy the engulfed bacteria.
A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber.[1] It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. Synaptic transmission at the neuromuscular junction begins when an action potential reaches the presynaptic terminal of a motor neuron, which activates voltage-dependent calcium channels to allow calcium ions to enter the neuron. Calcium ions bind to sensor proteins (synaptotagmin) on synaptic vesicles, triggering vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft. In vertebrates, motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (nAChRs) on the cell membrane of the muscle fiber, also known as the sarcolemma. nAChRs are ionotropic receptors, meaning they serve as ligand-gated ion channels. The binding of ACh to the receptor can depolarize the muscle fiber, causing a cascade that eventually results in muscle contraction.
Neuromuscular junction diseases can be of genetic and autoimmune origin. Genetic disorders, such as Duchenne muscular dystrophy, can arise from mutated structural proteins that comprise the neuromuscular junction, whereas autoimmune diseases, such as myasthenia gravis, occur when antibodies are produced against nicotinic acetylcholine receptors on the sarcolemma.
