The process of respiration system would not function well if the lungs was made up of only one big alveoli.
<u>Explanation:</u>
The main role of alveoli is to help the lungs to breath, for ventilation, diffusion and perfusion. The process of respiration system would not function well if the lungs was made up of only one big alveoli.
Alveoli are tiny to help the flow of oxygen and carbon dioxide, it helps the oxygen flow into the lungs and remove the carbon dioxide. If the alveoli is just one and big, then it would be hard to flow the oxygen through lungs and remove the carbon dioxide.
Therefore, it is good to have many tiny alveoli than one big one or the rib cage that protect the lungs could go through some damages.
Answer:
The food chain describes who eats whom in the wild. Every living thing—from one-celled algaeto giant blue whales—needs food to survive. Each food chain is a possible pathway that energy and nutrients can follow through the ecosystem.
For example, grass produces its own food from sunlight. A rabbit eats the grass. A fox eats the rabbit. When the fox dies, bacteria break down its body, returning it to the soil where it provides nutrients for plants like grass.
Of course, many different animals eat grass, and rabbits can eat other plants besides grass. Foxes, in turn, can eat many types of animals and plants. Each of these living things can be a part of multiple food chains. All of the interconnected and overlapping food chains in an ecosystem make up a food web.
The most important idea is that the genetic material of any organism must be able to accurately replicate itself at least every generation (or for multicellular organisms at each cell division).
Base pairing (A-T or U and C-G)allows DNA and RNA (eg in polio virus, see Wikipedia page on RNA dependent RNA polymerase) to create a copy of themselves, when the appropriate enzymes are present. Proteins have no way of making a copy of themselves.
Stability is probably the main reason DNA is the most common genetic material. DNA has no enzymatic activity and was probably selected for to maintain the integrity of the genetic material (rather than having to perform a function for the cell/virus, during which it may be destroyed). The double helix structure also protects its integrity, and proofreading enzymes have also evolved which correct most of the mistakes made at DNA replication. RNA viruses don't have this mechanism- which could be said to be an advantage (as they can rapidly change and therefore avoid their hosts' immune systems), however in non-parasitic organisms most mutations in a gene would lead to a loss of an essential function and the extinction of that genome.
I don't think either of these reasons are relevant, but I think the main reasons retroviruses convert their RNA to DNA are so they can use the host cell's replication machinery (this was they do not need to encode as many genes), and secondly they need avoid the antiviral mechanisms of the cell, which would destroy any double stranded RNA molecules found (even if the virus was single stranded, dsRNA would have to be produced at replication).
The answer is “Chromosomes are made of DNA!”
From the options given above, the two structures that will provide positive identification of a plant cell under a microscope are CHLOROPLAST AND LARGE CENTRAL VACUOLES.
Plant cells have some cell organelles which is unique to them, these organelles are not found in animal cells. Examples of such organelles are chloroplasts, large central vacuole, cell wall, etc. The chloroplast found in plant cells help the plants to trap energy from the sun during the process of photosynthesis. The large central vacuole found in plants play a critical role in turgor pressure of plants.
