Question

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Determine if the following statement is true or false and why: All organisms make their own food, but plants are the only kind to do so using sunlight. • • • A. False, all organisms can use sunlight to make food. B. False, plants cannot make their own food. C. True • D. False, not all organisms can make their own food, only plants and some bacteria.

Answer 1

1. Option 'D' is the correct one.

Plants which have chlorophyll in their cells can make own food by photosynthesis. Cyanobacteria or blue-green algae (Nostoc sp., Oscillatoria sp., Anabaena sp., etc.), some purple bacteria (Rhodospirillum sp., Rhodobacter sp., etc.) are photosynthetic also. These bacteria use bacteriochlorophyll for photosynthesis. On the other hand animals, insects, fungi are heterotrophs, i.e., they collect food material from other organisms. So that we can say neither all organisms can use sunlight to make food (option A) nor plants cannot make their own food (option B).

2. Option 'B' is the correct one.

Six molecules of carbon dioxide and six molecules of water are used in photosynthesis in the presence of light to produce one molecule of glucose and six molecules of oxygen.

Photosynthesis has two main phases -

A. Directly light dependant reaction- absorption of energy from the photons of sunlight and production of oxygen molecules by photolysis of water, production of ATP.

B. Indirectly light dependant reaction- production of glucose, sucrose, starch and NADP+ .

3. Option 'B' is the correct one.

In any industry, the source of energy used to operate a machine is either fossil fuels or electricity. Burning of fossil fuels releases carbon dioxide directly into the atmosphere. Production of electricity is done mainly by burning coals or fossil fuels. Thus using electricity indirectly increases the carbon dioxide level in our atmosphere.

Option 'A' is not correct because the increased level of carbon dioxide triggers global warming, i.e., global warming is the consequence not the main cause of increased carbon dioxide level in our atmosphere.

Option 'C' is not correct because the carbon cycle helps in balancing the level of atmospheric carbon dioxide. This cycle does not always increase the level of atmospheric carbon dioxide.

Option 'D' is not correct because antarctic ice cores control the level of seawater and reduce atmospheric carbon dioxide level by carbon sequestration.

4. Option 'A' is the correct one.

In meiosis 1 the number of chromosomes in daughter cells are half of the number of chromosomes of the mother cell. That is why meiosis 1 is called the reductional division.

In mitosis, meiosis 2, binary fission the number of chromosomes in daughter cells remains the same as the parent cell. That's why option 'B', 'C', 'D' are false.

5. Option 'A' is the correct one.

Liger is a hybrid between a male lion and a female tiger. On the other hand, a hybrid between a male tiger and a female lion is called a tigon. These hybrids are not natural, they are produced artificially.

Option 'B' is false because, a liger cannot be considered as a separate species as they are the production of artificial interbreeding experiments.

Option 'C' is false because only female ligers are fertile, whereas the male ligers are sterile.

Option 'D' is false because ligers exist in man-made captivity like zoos.

6. Option 'B' is the correct one.

Enzymes are the biomacromolecules, which are responsible for catalyzing biochemical reactions. The main structure of an enzyme is built up by proteins only. Sometimes nucleic acids, carbohydrates, lipids may be attached with enzymes as additional structures.

Nucleic acids, carbohydrates and lipids cannot construct the main part of enzymes, only proteins can do this.

7. Option 'B' is the correct one.

Renewable resources are those energy sources that can be obtained or produced indefinitely. Those are not limited in our nature. Natural gas is a resource that is limited in our nature. A certain amount of natural gas is stored below the earth crust. They can be collected by excavation. Hence, natural gas is not a renewable resource.

Solar power, wind and hydropower are not limited in our nature, they occur indefinitely. Hence these are renewable resources that can reduce our reliance on fossil fuels.