Answer:
B. False
Explanation:
Child-birth in mammals is not an example of endocrine-controlled negative feedback, because the production of oxytocin during childbirth doesn't result in additional oxytocin being synthesized by the posterior pituitary gland.
Oxytocin is the enzyme which is necessary at the time of birth in order to contract the walls of the uterus and expel the baby out of the body. Oxytocin levels rise at the onset of labour,causing regular contractions of womb and abdominal muscles. Oxytocin induced contractions become stronger and more frequent without the influence of progesterone and estrogen, which at high levels prevent labour.
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Answer:
C. two tetramers of histone proteins
Explanation:
The nucleosome core particle is responsible for packaging DNA in the chromosomes. The protein components that make up the nucleosome core are two tetramers of histone proteins. One of which is composed of two units each of histones H2A and H2B, while the other one is composed of two units each of histones H3 and H4. Thus making up the entire protein component of the nucleosome core.
Answer:
B. sarcoplasmic reticulum ; sarcoplasm
Explanation:
A neural signal is the electrical trigger for calcium release from sarcoplasmic reticulum into the sarcoplasm. Electrical signals, called action potentials, travel along the neuron's axon connecting to individual muscle fibers at a neuromuscular junction. Neuron action potentials cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can diffuse across the synaptic cleft and bind to a receptor molecule on the motor end plate.
Answer:
Option B, After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus
Explanation:
Cleaving of nuclear localization signals occurs before the transportation into the nucleus. Before that it is responsible for sending nuclear protein continuously after every cell division leaving very little protein in the cytoplasm. Once the cleaving occurs, the nuclear localization signals, no more protein can be transmitted thereby leaving very little protein tail segments in the nucleus. Also the signal sequences on the proteins are removed once they are trans located.
Hence, option B is correct
