Answer:
The environment usually refers to all the biotic and the abiotic components that are surrounding us. This environment undergoes changes depending upon various factors which can be natural and/or due to the anthropogenic activities.
When there occur rapid environmental changes, then it directly affects the lives of species, in different ways, such as-
- Those species that are comparatively weaker in adapting according to the environmental changes that occur, will not be able to cope up with the new environment. They may become extinct.
- Some variety of species will be able to adapt to the new environment because of their easily adapting capabilities.
- The traits that will be developed within the species in the new environment will be more successful in terms of reproduction.
- The previously existed traits may have a harmful impact in the newly formed environment.
Before the Calvin cycle begins the energy is stored in bonds of ATP
If the sperm cell fertilises the ovum, and implantation does not occur, then the corpus luteum degenerates and it turns into corpus albicans, stopping progesterone secretion. If fertilisation occurs and implantation also, the syncytiotrophoblast, the "root part" of the blastocyst (one of the early structures originated from the zygote), produces a hormone that is called <span>human chorionic gonadotropin (hCG). The hCG is what makes the corpus luteum keep secreting progesterone and maintain itself. The progesterone will then help keep the endometrium and, therefore, allow the development of the embryo to happen.</span>
Answer:
A- Acetylcholine is released by axon terminals of the motor neuron.
Explanation:
The general mechanism of muscle contraction can be explained as follows:
a) The action potential which is generated, travels along the motor nerve to its ends on muscle fiber (or motor end plate) at the neuro-muscular junction.
b) The nerve endings then secrete small amounts of neurotransmitter called acetylcholine.
c) The actylecholine binds to the receptors on the membrane of muscle fiber and opens the voltage gated sodium channels.
d) Opening of these channels leads to flow of large quantities of sodium ions into the muscle fiber which ultimately results in initiation of action potential in muscle fiber.
e) This action potential depolarizes the fiber including the T-tubules, triggering the release of calcium ions from sarcoplasmic reticulum.
f) The calcium ions thus released initiated the process of muscle contraction.
