Answer: C. Homologous chromosomes are separated in meiosis but not in mitosis.
Explanation: There are two main types of division that take place in eukaryotic cells, mitosis, and meiosis. Mitosis is the type of division that is used for growth, repair, and replacement of tissues. Therefore it is not necessary that the cells have different chromosome numbers or are varied genetically in the daughter cells in the case of mitosis.
Meiosis is the division that takes place to form the gametes for sexual reproduction. It is important in the first stages of meiosis I, to introduce variation and to halve the chromosome number.
Chromosomes numbers are halved (from 46 to 23) during meiosis I because the gametes (sperm and egg) come together and fuse during fertilization to form a zygote. When this fusion occurs (23 from the zygote and 23 from the egg), the chromosome number needs to be returned to that of the parent cell (46).
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Genetic variation is introduced during synapsis which only occurs in meiosis, not mitosis. Homologs exchange genetic information during crossing over of synapsis. Entire chromosomes also separate during meiosis I.
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At the end of meiosis, four genetically unique cells are produced with half the number of chromosomes as the parent cell (23 cromosomes) . After the process of mitosis is completed, two cells genetically identical to each pther are produced and have the same number of chromosomes as the parent cell (46 cromosomes).
Genetic variation is actually important because of changing environmental conditions.
Answer:
A piloted spacecraft is always manned
Banana peels can be decomposed by bacterial action, so they are biodegradable.
Well I'm not exactly certain where the teacher is going with this, but an often used example is red blood cells (RBCs) aka: erythrocytes.
RBCs are suspended in blood plasma as they flood through vessels around and around the body, so the osmolarity (amount of small particles that affect osmosis) must remain relatively constant. This is termed "isotonic", meaning the same amount of osmosis-influencing particles that are there inside the RBCs' cytosol, within their plasma membranes.
If the plasma osmolarity get too high, called hypertonic (as with extra salt particles) then water inside the RBCs will have an osmotic force driving it out of the cells' membranes, to flow where there are more salt particles. This will lead to cell shrinkage (called "crenation").
Counter to that, if the plasma osmolarity gets too low, as due to low plasma salt with excessive water intake (for example from the condition "water intoxication"), then the plasma will be hypotonic with respect to the intracellular cytosol concentration. This can result in water rushing into the RBCs' membranes via osmosis, causing the cells to swell from discs into spheres (balls), or even rupture and burst (a phenomenon called "hemolysis").
HOPE THOSE EXAMPLES HELP!!
Answer:
The long strands of double-helical DNA wrap around histone proteins. The wrapping goes on and on to achieve the secondary and tertiary level of packing. In the end, the whole thing is highly packed enough to fit inside the nucleus of a single cell.
Explanation:
