Biology And Human Welfare

Step 1: Biofertilizer definition.
Biofertilizers are substances that contain living microorganisms which promote plant growth by increasing the supply or availability of primary nutrients to the host plant. These are natural fertilizers which help in maintaining soil fertility.
Step 2: Analyze the options.
- Azolla: A water fern that is a well-known biofertilizer. It is used as a nitrogen-fixing biofertilizer in rice fields. - Marsilea: While it is a water fern, it is not commonly used as a biofertilizer. - Pteridium: Known as bracken fern, is not commonly associated with biofertilization. - Salvinia: This is another aquatic fern but it does not have significant biofertilizer properties compared to Azolla.
Step 3: Conclusion.
Azolla is widely recognized for its ability to fix nitrogen in rice paddies and is used as an excellent biofertilizer.
Final Answer:

Step 1: Understand the source of cloves.
Cloves are obtained from the dried flower buds of the clove tree, Syzygium aromaticum. These buds are harvested before they bloom.
Step 2: Review the options.
- Clove is obtained from the bud, not the flower, fruit, or seed. - The flower blooms after the bud is harvested to be dried and used as the spice clove.
Step 3: Conclude.
Cloves come from the bud of the clove tree, making option (B) the correct answer.
Final Answer:

Step 1: Understand the function of statins.
Statins are drugs commonly prescribed to lower cholesterol levels in the blood. They work by inhibiting HMG-CoA reductase, an enzyme responsible for producing cholesterol in the liver.
Step 2: Review the options.
- Statin is the correct choice as it directly lowers cholesterol in the blood. - Cyclosporin is an immunosuppressant used to prevent organ transplant rejection. - Lipase is an enzyme that breaks down fats but is not used for lowering cholesterol. - Streptokinase is used to dissolve blood clots, not to lower cholesterol.
Step 3: Conclude.
Statins are the correct medication used to lower cholesterol levels, making option (A) the correct answer.
Final Answer:

Step 1: Understand quinine.
Quinine is a compound obtained from the bark of the Cinchona tree, commonly used for the treatment of malaria.
Step 2: Review the options.
- Canabis is the source of marijuana, not quinine.
- Cinchona is the correct source of quinine.
- Poppy is the source of opium, not quinine.
- Eucalyptus is a source of oil but not quinine.
Step 3: Conclude.
Cinchona is the source of quinine, making option (B) the correct answer.
Final Answer: