Answer:
Explanation:
1) Excitation brings about contraction.
2) Contraction leads to an increase in blood pressure.
3) Changes in blood pressure results in the opening and closing of the heart valves.
4) The opening and closing of heart valves then regulates the flow of blood and it's volume.
Answer: Option D " all of the above "
Explanation: DNA can be a great source of information when used as a forensic evidence. This technique has many advantages and disadvantages when used as a source of information in case of crime.
Identical twins: There are some common fragments of DNA that is same in identical twins so it can be a difficulty in deciding the criminal.
Not enough of a sample: DNA should be present in a detectable amount to be used an sample for evidence, less than this detectable amount is a waste and cannot be used as a sample for evidence.
Contaminated and degraded sample: If the sample of DNA is contaminated or degraded then the result might be incorrect and might not be used as a sample for forensic evidence.
Hence, the correct answers are all of the above.
Answer:
Relaxation of the dartos muscle.
Explanation:
Testes are present in scrotum outside the pelvic cavity to maintain the temperature about 2-3 degrees Celsius below the body temperature as required for sperm production. Dartos muscle is the layer of smooth muscle located in the superficial fascia. The contraction of dartos muscle serves to make the skin of the scrotum wrinkled and tight.
During hot weather, the dartos muscle relaxes and makes the surface of scrotum less wrinkled to increase the loss of the heat from its surface. The increased heat loss from the surface of scrotum due to relaxed dartos muscles keeps the testes protected from heat.
Prophase I
The chromosomes condense, and the nuclear envelope breaks down & crossing-over occurs.
Metaphase I
Pairs of homologous chromosomes move to the equator of the cell.
Anaphase I
Homologous chrmosomes move to the oppisite poles of the cell.
Telophase I and Cytokinesis
Chromosomes gather at the poles of the cells & the cytoplasm divides.
Prophase II
A new spidle forms around the chromosomes.
Metaphase II
Chromosomes line up at the equator.
Anaphase II
Centromeres divides & chromatids move to the opposite poles of the cells.
Telophase II and Cytokinesis
A nuclear envelope forms around each set of chromosomes & the cytoplasm divides.
what are the answer choices
