Answer:
<em>The correct option is cell surface markers.</em>
Explanation:
The immune cells of our body detect foreign particles and generate responses so that our body can get rid of them. The foreign particles are often termed as antigens.
The immune cells such as antibodies possess cell surface receptors which detect the foreign objects or antigens. When the cell surface receptors detect any antigen they immediately recognize that a foreign particle has invaded the body and they then identify it and start to generate response.
Answer:
In animal field studies, why do scientists usually try to work without making the animals aware that the humans are present? It is necessary to observe the animals without disturbing them. When a controlled experiment is not possible, why do scientists try to identify as many relevant variables as possible?
The right options are; makes food for all organisms, adds oxygen to the atmosphere, is a source of medicines and fibers, is a source of building materials and it provides animal habitat.
Photosynthesis is a process by which green plants and some other autotrophs use light energy in chloroplasts to generate carbohydrates (food) from carbon dioxide and water while oxygen is being released as a by-product. Photosynthesis is essential to all living organisms on earth because it is the main source of oxygen in the atmosphere. Photosynthesis provides animal habitat, it provides food for all organisms (directly for plants and indirectly for animals). Plants and trees produce their foods through photosynthesis and are used as medicines and fibers, and as building materials.
Answer:
Explanation:
There are many examples of fossils found on separate continents and nowhere else, suggesting the continents were once joined. If Continental Drift had not occurred, the alternative explanations would be:
The species evolved independently on separate continents – contradicting Darwin’s theory of evolution.
They swam to the other continent/s in breeding pairs to establish a second population.
Nutrients cross the membrane wall with the help of protein channels.
