Answer:
The correct answers: A, B, C.
Explanation:
- Lipid bilayer is made of two layers of phospholipids, where each phospholipid molecule is made up of a glycerol which is attached to a phosphate group and two fatty acid chains by ester bonds.
- The phosphate groups being hydrophilic are directed towards the outside of the bilayer. The fatty acid chains (saturated or unsaturated) being hydrophobic are directed towards the inside of the bilayer.
- These fatty acid chains are not static and are capable of moving laterally in the bilayer, giving the bilayer the characteristics of fluidity.
- The fluidity is mainly provided by the presence of unsaturated (with one or multiple double bonds) fatty acid. The presence of double bonds results in the fatty acid molecules to have a bent shape and this increases the area occupied by each such unsaturated fatty acid molecule. The free area available allows the lateral movement of the fatty acid molecules.
- According to option A, long chain fatty acids tend to occupy more space within the lipid bilayer. This reduces the free space available for the movement of the lipid molecules.
- According to option B, saturated fatty acids are those which lacks any double bonds and the carbon atoms are attached by single bonds. Therefore, these molecules are straight in shape and occupy maximum area in the lipid bilayer. This reduces the space available for the free movement of fatty acid molecules, thereby making the membrane less fluid in nature.
- According to option C, cholesterol is a type of lipid molecule. They remain interspersed in between lipid molecules. At high temperatures, they prevent the lipid molecules from getting excessively fluid by filling in the gaps in between the lipid molecules and at very low temperatures they prevent the stiffening of the lipid molecules by getting associated with each other. At room temperature, they stabilise the lipid molecules between whom they remain interspersed and also reduce the free space in between them thereby reducing the lateral movement. This way they reduce the fluidity.
Humans disturb the earth and because of this, the earth is weakened.
Answer:
Some fish or amphibians secrete <u>mucus that retains water or oxygen particles and then it passes into their body.
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Explanation:
Many amphibians and fish have thin and in many cases slippery skin.
This is because some species secrete slimy substances through the skin, keeping it wet.
Since some fish or amphibians cannot ingest water directly, they need a way to stay hydrated.
This viscosity or mucus makes possible for the animal to come into contact with water and oxygen, and then ingest them.
In addition to this in some amphibians, mucus disperses secretions from other glands, the poisonous glands, which serve as a shield for predators.
Sometimes called mechanical weathering, physical weathering is the process that breaks rocks apart without changing their chemical composition. These examples illustrate physical weathering:
Swiftly moving water
An individual's blood pressure, body temperature, and heart rate start to soar to dangerously high levels.
