Answer:
D. They define geological periods because scientists use them as reference points for tracking the history of the earth.
Explanation:
Catastrophic events related to changes in geological timeline are very useful in defining geological periods.
These events have very significant appearance in the geological record and can be used to determine the history of the earth.
The catastrophic events usually culminates into extinction cycles or termination of some organisms from the earth surface.
Geologists use these events that are often wide spread to delineate geological periods.
Answer:
In chemical transmission the release of chemical messengers known as neurotransmitters occurs. Neurotransmitters carry information from the presynaptic or transmitter neuron to the postsynaptic or recipient cell.
As you may recall from the article on the structure and function of the neuron, synapses are usually formed between the nerve terminals - axon terminals - of the sending neuron and the cell body or dendrites of the receiving neuron.
Scheme of synaptic transmission. An action potential travels through the axon of the presynaptic or emitting cell, and reaches multiple axon terminals branching from the axon. The axon terminal is adjacent to the dendrite of the postsynaptic or recipient cell. This place of close connection between axon and dendrite is the synapse.
A single axon can have multiple ramifications, which allows it to synapse with several postsynaptic cells. Similarly, a single neuron can receive miles of synaptic inputs from many different presynaptic or emitting neurons.
Within the axon terminal of a transmitter cell there are many synaptic vesicles. These are membranous spheres full of neurotransmitter molecules. There is a small space between the axon terminal of the presynaptic neuron and the postsynaptic cell membrane, this space is called synaptic space.
Answer:
c. decrease rate of muscle activity
Answer: It is C.hydrolysis
Explanation:
Answer:
E) sister chromatids separate during anaphase of meiosis I.
Explanation:
Chromosomes are composed of two chromatids which are joined together through centromere. Chromosomes get doubled its chromatids during its S phase of Interphase. Although chromosomes number remains the same as after S phase but number of chromatids becomes double.
For Example:
In humans 46 chromosomes are present before S phase and 46 chromosomes after S phase. only difference is that chromatids before S phase is 46 in number while after S phase it becomes double i.e becomes 92.
During Prophase 1 of Meiosis 1 these 46 chromosomes with 92 chromatids get arranged in manner that homologous chromosome pair comes close together and form 23 pairs.
During Metaphase 1: These 23 pairs get arranged in center and attached with spindle fiber present inside cells. Each spindle fiber attach to one member of the pair in a manner that 23 spindle fibers from one side of pole attached to one member of homologous chromosome pairs and 23 spindle fibers from other side of pole attached to other member of homologous chromosome pairs.
In Anaphase 1 of Meiosis 1 these spindle fibers get contracted and pulled attached chromosome along with them towards opposite poles. In this manner chromosome numbers in Meiosis become half as compared to the Mitosis
So Correct Answer of the question is
E. sister chromatids separate during anaphase of meiosis I.
