user: Q: What is the exchange of plasmids by prokaryotes called?   Read this paragraph and choose the correct option from the provided answers:  For natural selection to take place, organisms must vary in their traits. Asexual reproduction results in offspring that are all the same. They are also identical to the parent cell. So how can prokaryotes increase genetic variation? They can exchange plasmids. This is called genetic transfer . It may happen by direct contact between cells. Or a "bridge" may form between cells. Genetic transfer mixes the genes of different cells. It creates new combinations of alleles.   Choices:  - biochemical transfer  - artificial transfer  - transcription  - genetic transfer   A:
genetic transfer


(Question)
Q: What explains why two different species cannot occupy the same niche in the same place for very long?   Read this paragraph and choose the correct option from the provided answers:  A given habitat may contain many different species, but each species must have a different niche. Two different species cannot occupy the same niche in the same place for very long. This is known as the competitive exclusion principle . If two species were to occupy the same niche, what do you think would happen? They would compete with one another for the same food and other resources in the environment. Eventually, one species would be likely to outcompete and replace the other.   Choices:  - evolution  - natural selection  - survival exclusion princple  - competive exclusion princple   A:
(Answer)
competive exclusion princple


Ques: Q: What is the“packet” of energy called that the nucleus emits during gamma decay?   Read this paragraph and choose the correct option from the provided answers:  Gamma rays are produced during gamma decay of an excited nucleus. During gamma decay, the nucleus emits a “packet” of energy called a gamma particle.   Choices:  - transient particle  - radioactive particle  - ultraviolet particle  - gamma particle   A:
Ans: gamma particle


(Q).
Q: The nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by what?   Read this paragraph and choose the correct option from the provided answers:  The Nitrogen Cycle Getting nitrogen into the living world is difficult. Plants and phytoplankton are not equipped to incorporate nitrogen from the atmosphere (which exists as tightly bonded, triple covalent N2) even though this molecule comprises approximately 78 percent of the atmosphere. Nitrogen enters the living world via free-living and symbiotic bacteria, which incorporate nitrogen into their macromolecules through nitrogen fixation (conversion of N2). Cyanobacteria live in most aquatic ecosystems where sunlight is present; they play a key role in nitrogen fixation. Cyanobacteria are able to use inorganic sources of nitrogen to “fix” nitrogen. Rhizobium bacteria live symbiotically in the root nodules of legumes (such as peas, beans, and peanuts) and provide them with the organic nitrogen they need. Free-living bacteria, such as Azotobacter, are also important nitrogen fixers. Organic nitrogen is especially important to the study of ecosystem dynamics since many ecosystem processes, such as primary production and decomposition, are limited by the available supply of nitrogen. As shown in Figure 46.17, the nitrogen that enters living systems by nitrogen fixation is successively converted from organic nitrogen back into nitrogen gas by bacteria. This process occurs in three steps in terrestrial systems: ammonification, nitrification, and denitrification. First, the ammonification process converts nitrogenous waste from living animals or from the remains of dead animals.   Choices:  - algae  - pollen  - viruses  - bacteria   A:
(A).
bacteria


Ques:Q: Giardiasis and malaria are diseases caused by what organism?   Read this paragraph and choose the correct option from the provided answers:  Many human diseases are caused by protists. Most of them are caused by protozoa. They are parasites that invade and live in the human body. The parasites get a place to live and nutrients from the human host. In return, they make the host sick. Examples of human diseases caused by protozoa include giardiasis and malaria.   Choices:  - worms  - larvae  - bacteria  - protozoa   A:

Ans:protozoa


Q: What is the outer layer of an axon that acts like a layer of insulation, similar to the plastic that encases an electrical cord?   Read this paragraph and choose the correct option from the provided answers:  The axon of many neurons has an outer layer called a myelin sheath (see Figure above ). Myelin is a lipid produced by a type of a glial cell known as a Schwann cell. The myelin sheath acts like a layer of insulation, similar to the plastic that encases an electrical cord. Regularly spaced nodes, or gaps, in the myelin sheath allow nerve impulses to skip along the axon very rapidly.   Choices:  - lipids sheath  - nerve sheath  - layer sheath  - myelin sheath   A:


assistant: myelin sheath