NMMS - National Means-cum-Merit Scholarship Science: Cell Structure and Microorganisms Questions and Answers — Questions and Answers
Question 1: A student observes a cell under a microscope and notes the presence of a cell wall, a large central vacuole, and chloroplasts. Based on these observations, the student should conclude that the cell is most likely from which type of organism?
- A fungus
- An animal
- A plant (Correct answer)
- A bacterium
Correct answer: A plant
The presence of a rigid cell wall, a large central vacuole for maintaining turgor pressure, and chloroplasts for photosynthesis are all hallmark features of a plant cell. Animal cells lack a cell wall, large central vacuole, and chloroplasts. Fungal cells have a cell wall but lack chloroplasts. Bacterial cells have a cell wall but lack a nucleus and other membrane-bound organelles like large vacuoles and chloroplasts.
Question 2: Which of the following correctly matches the cell organelle with its primary function?
- Ribosome - Energy production
- Mitochondrion - Protein synthesis
- Nucleus - Controls all cellular activities (Correct answer)
- Cell Membrane - Produces lipids
Correct answer: Nucleus - Controls all cellular activities
The nucleus contains the cell's genetic material (DNA) and acts as the control center, directing all cellular activities like growth, metabolism, and reproduction. Mitochondria are responsible for energy production (the 'powerhouse'), ribosomes are the sites of protein synthesis, and the cell membrane controls what enters and leaves the cell.
Question 3: A food scientist is working on a new method of food preservation that involves removing as much water as possible from the food product. This method is effective because it inhibits the growth of microorganisms primarily by:
- Increasing the food's acidity
- Removing the oxygen that microbes need
- Lowering the temperature to freezing
- Limiting the water available for microbial metabolic processes (Correct answer)
Correct answer: Limiting the water available for microbial metabolic processes
Microorganisms, like all living things, require water for their metabolic processes, growth, and reproduction. The method of drying or dehydration removes moisture from food, which creates an environment where most bacteria, yeasts, and molds cannot thrive. While changing acidity (pickling), removing oxygen (vacuum packing), and freezing are also preservation methods, dehydration specifically targets the availability of water.
Question 4: Which of the following diseases is caused by a protozoan and is commonly transmitted by mosquitoes?
- Tuberculosis
- Malaria (Correct answer)
- Cholera
- Typhoid
Correct answer: Malaria
Malaria is a serious disease caused by a protozoan parasite of the genus Plasmodium. It is transmitted to humans through the bite of an infected female Anopheles mosquito. Tuberculosis, Cholera, and Typhoid are all caused by bacteria, not protozoa.
Question 5: A student notices that when dough is prepared for making bread, it increases in volume if left in a warm place for a few hours. Which microorganism is responsible for this process, and what is the process called?
- Bacteria, Decomposition
- Yeast, Fermentation (Correct answer)
- Algae, Photosynthesis
- Virus, Replication
Correct answer: Yeast, Fermentation
Yeast, a type of fungus, is added to dough to make it rise. The yeast undergoes a process called fermentation, where it converts sugars in the dough into carbon dioxide gas and alcohol. The bubbles of carbon dioxide gas get trapped in the dough, causing it to expand and increase in volume.
Question 6: Which of the following statements accurately describes a key difference between a virus and a bacterium?
- Bacteria are multicellular, while viruses are unicellular.
- Viruses can reproduce on their own, whereas bacteria require a host cell.
- Bacteria have a cellular structure with organelles, while viruses are non-cellular and much simpler. (Correct answer)
- Viruses cause diseases like typhoid, while bacteria cause the common cold.
Correct answer: Bacteria have a cellular structure with organelles, while viruses are non-cellular and much simpler.
Bacteria are single-celled organisms with a complete cellular structure, including a cell wall, cell membrane, and cytoplasm with ribosomes. Viruses are much simpler and are not considered cells; they consist of genetic material (DNA or RNA) enclosed in a protein coat and can only replicate by infecting a living host cell. Bacteria are unicellular, not multicellular. Bacteria can reproduce on their own, while viruses require a host. Bacterial diseases include typhoid, while viruses cause the common cold.
NMMS - National Means-cum-Merit Scholarship Science: Cell Structure and Microorganisms Questions and Answers
A student observes a cell under a microscope and notes the presence of a cell wall, a large central vacuole, and chloroplasts.
Based on these observations, the student should conclude that the cell is most likely from which type of organism?