A) <u>Mutation</u> is the original source of variations for plants and other organisms which develops differences among their respective species
Explanation:
Genetic variation leads to the natural differences between each individual and among individuals of a species. The main cause for this variation is due to alleles that cause variations in the composition of genes or the DNA sequences.
A mutation is a genetic variation which leads to the creation of a new allele in a species population. Each variation in the DNA sequence leads to an allele formation and each allele leads to a difference in character or trait between individuals since they are the alternate version of the original genes.
Although genetic variations could be brought about by crossing over, random fertilization, or independent assortment; mutation is the original source because it provides the basic raw material for all the evolutionary changes.
Parasite: Parasites are different from predators because parasites only take resources from one host, whereas predators eat many prey. A good example of this is the trematode parasite Schistosoma mansoni. An adult schistosome parasite lives inside of just one human host
Answer:
The correct answer is: (A).
Explanation:
- In the question, it is mentioned that the algae can grow under the conditions of "enough sunlight" and "enough nutrients".
- Sunlight reaches the algae, by first falling on the surface made up of ice and snow and then refracting from there into the top layer of the ice where the algae grows.
- However, the capability of both snow and ice to reflect sunlight is far more than that of refracting sunlight.
- Therefore, the amount of light received by the algae is similar in absence or presence of the layer of snow on the top layer of ice.
- However, on deposition of snow on the layer of the ice, the weight of the ice increases and it sinks below into sea water.
- This allows more nutrient rich sea water to percolate into the ice and reach the algae.
- The algae receive more nutrients from the sea water and hence is capable undergoing better metabolism and growth.
- Hence, more algae are produced under such a situation.
Answer:
Cells divide twice
Explanation:
Meiosis may be defined as the process of cell division in which a single cell divides to give four daughter cells and each daughter cells have half number of chromosomes.
Meiosis is also known as reduction division as the chromosome number reduces upto half in the progeny cells as compared with the parent cell. The cells divide twice in meiosis and give rise to four daughter cells.
Thus, the correct answer is option (4).
Answer:
If your just looking for a description here you go.
Explanation:
Most spiral galaxies contain a central bulge surrounded by a flat, rotating disk of stars. The bulge in the center is made up of older, dimmer stars, and is thought to contain a supermassive black hole. Approximately two-thirds of spiral galaxies also contain a bar structure through their center, as does the Milky Way.
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