Answer:
the correct answer is phloem it is not there
Explanation:
A model is used to help scientists visualise things that they cannot actually see. It can be thought of as a thinking tool, to help form explanations. Models are useful simplifications to aid understanding. ... It can then be used to explain further phenomena and to make predictions of future behaviour.
Option D – amphibians may use their skin for gas exchange is the characteristic feature of amphibians that differs from reptiles.
Explanation:
The amphibian skin is moist, thin and marbled and supplied by blood vessels running on its surface. The moisture present in the skin dissolves the oxygen present in its surrounding which is absorbed by the blood vessels. Special glands help the amphibians to keep the skin moist.
The very thick and tough scales present on the reptiles prevent them to absorb oxygen through their skin. Hence, they breathe and respire through their lungs.
Amphibians have three-chambered heart. They do not develop amniotic eggs. Adult amphibians although spend much time on land, they breed only in water due to the absence of amniotic sac
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Lipids are a class of organic compounds, which suits best under the column macromolecules on the hierarchy of biological organization.
Biological organization refers to the hierarchy of composite biological systems and compositions, which illustrate life using a reductionistic method. The conventional hierarchy moves from an atom to more complex biospheres.
Each of the level in the hierarchy signifies an enhancement in the organizational complexity, with each component being mainly comprised of the previous basic unit level.
