1. Which structure is present in both plant and animal cells?
A. Cell wall
B. Chloroplast
C. Nucleus
D. Large central vacuole
Answer: C. Nucleus
2. Which feature helps distinguish a typical plant cell from an animal cell?
A. Presence of cytoplasm
B. Presence of a cell membrane
C. Presence of a nucleus
D. Presence of a cell wall
Answer: D. Presence of a cell wall
3. The long and branched shape of a nerve cell is mainly related to its ability to:
A. Store food
B. Carry signals over distances and connect with other cells
C. Produce chlorophyll
D. Absorb minerals from soil
Answer: B. Carry signals over distances and connect with other cells
4. A collection of similar cells working together to perform a particular function is called:
A. Organ
B. Tissue
C. Organ system
D. Organism
Answer: B. Tissue
5. Which sequence correctly represents increasing biological organisation?
A. Cell $\rightarrow$ Organ $\rightarrow$ Tissue $\rightarrow$ Organ system
B. Tissue $\rightarrow$ Cell $\rightarrow$ Organ $\rightarrow$ Organism
C. Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system
D. Organ $\rightarrow$ Tissue $\rightarrow$ Cell $\rightarrow$ Organism
Answer: C. Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system
6. Which organism moves by forming pseudopodia?
A. Paramecium
B. Amoeba
C. Bacterium
D. Yeast
Answer: B. Amoeba
7. Paramecium mainly uses which structures for locomotion?
A. Flagella
B. Pseudopodia
C. Cilia
D. Roots
Answer: C. Cilia
8. In an activity involving soil suspension, which microorganisms may commonly be observed?
A. Bacteria and fungi
B. Viruses and algae only
C. Amoeba and nerve cells
D. Plastids and chloroplasts
Answer: A. Bacteria and fungi
9. Which pair plays an important role in decomposing organic waste during compost formation?
A. Viruses and protozoa
B. Fungi and bacteria
C. Nerve cells and muscle cells
D. Amoeba and Paramecium
Answer: B. Fungi and bacteria
10. Viruses are described as acellular because they:
A. Have many specialised cells
B. Are made of a single complete cell
C. Do not possess a normal cellular structure
D. Contain chloroplasts instead of nuclei
Answer: C. Do not possess a normal cellular structure
11. A typical virus contains:
A. Cytoplasm and mitochondria
B. DNA or RNA enclosed by a protein coat
C. Cell wall and chloroplast
D. Nucleus and vacuole
Answer: B. DNA or RNA enclosed by a protein coat
12. Why are viruses considered unusual compared with other organisms?
A. They are always multicellular
B. They show living characteristics only inside a host
C. They can perform photosynthesis
D. They contain tissues and organs
Answer: B. They show living characteristics only inside a host
13. Composting is considered environmentally friendly because it:
A. Increases the amount of non-biodegradable waste
B. Converts organic waste into useful manure
C. Prevents all microbial activity
D. Removes nitrogen from soil
Answer: B. Converts organic waste into useful manure
14. One major advantage of producing biogas from organic waste is that it:
A. Produces a non-renewable fuel
B. Increases landfill waste
C. Provides renewable fuel while helping manage waste
D. Stops all decomposition processes
Answer: C. Provides renewable fuel while helping manage waste
15. Which gas is mainly associated with biogas production from decomposing organic matter?
A. Oxygen
B. Nitrogen
C. Methane
D. Hydrogen
Answer: C. Methane
16. Bread dough becomes soft and expands after yeast is added because:
A. Yeast releases oxygen during respiration
B. Yeast produces carbon dioxide during fermentation
C. Yeast converts carbon dioxide into sugar
D. Yeast absorbs all the moisture from the dough
Answer: B. Yeast produces carbon dioxide during fermentation
17. Which condition is most favourable for converting milk into curd?
A. Very low temperature without bacteria
B. Warm conditions with Lactobacilli present
C. Completely dry conditions
D. Strong sunlight without microorganisms
Answer: B. Warm conditions with Lactobacilli present
18. Leguminous plants improve soil fertility mainly because their root nodules contain:
A. Lactobacillus
B. Rhizobium
C. Yeast
D. Amoeba
Answer: B. Rhizobium
19. The process by which Rhizobium converts atmospheric nitrogen into a form usable by plants is called:
A. Fermentation
B. Decomposition
C. Biological nitrogen fixation
D. Photosynthesis
Answer: C. Biological nitrogen fixation
20. A farmer grows peas without applying nitrogen fertiliser, yet the soil remains nitrogen-rich. What is the most likely reason?
A. Pea leaves directly release nitrogen gas into soil
B. Rhizobium in root nodules fixes atmospheric nitrogen
C. Yeast produces nitrogen during fermentation
D. Viruses convert soil minerals into nitrogen
Answer: B. Rhizobium in root nodules fixes atmospheric nitrogen
21. Microalgae are important in aquatic ecosystems because they:
A. Destroy oxygen in water
B. Act as a food source and produce oxygen through photosynthesis
C. Prevent all aquatic organisms from growing
D. Convert all water into carbon dioxide
Answer: B. Act as a food source and produce oxygen through photosynthesis
22. Why is the cell called the basic structural and functional unit of life?
A. Every cell is multicellular
B. It is the smallest unit capable of carrying out life processes
C. It is larger than every tissue
D. It can exist only inside an organ
Answer: B. It is the smallest unit capable of carrying out life processes
23. Which of the following is a unicellular organism?
A. Amoeba
B. Human being
C. Bean plant
D. Fish
Answer: A. Amoeba
24. Mould generally develops faster on moist bread kept in a warm kitchen than on bread stored in a refrigerator because:
A. Cold temperatures increase fungal reproduction
B. Warm and moist conditions favour fungal growth
C. Mould requires freezing temperatures
D. Refrigerators supply extra nutrients to fungi
Answer: B. Warm and moist conditions favour fungal growth
25. Curd kept outside for a long time during summer becomes excessively sour mainly because:
A. Lactobacilli become more active and produce more lactic acid
B. Yeast converts all the curd into methane
C. Rhizobium grows rapidly in the curd
D. Viruses begin photosynthesis
Answer: A. Lactobacilli become more active and produce more lactic acid
26. Which experimental setup would best test whether moisture is necessary for microbial growth on bread?
A. Keep two dry bread slices at different temperatures
B. Keep one moist and one dry bread slice under the same other conditions
C. Keep one bread slice in water and another in direct sunlight
D. Compare bread with milk
Answer: B. Keep one moist and one dry bread slice under the same other conditions
27. Which observation would support the conclusion that moisture promotes microbial growth?
A. The dry bread develops mould much faster
B. Both bread slices remain completely unchanged
C. The moist bread develops microbial growth faster than the dry bread
D. Microbes grow only when the bread is frozen
Answer: C. The moist bread develops microbial growth faster than the dry bread
28. Which of the following represents a useful role of microorganisms?
A. Causing food spoilage
B. Producing disease
C. Helping in compost formation
D. Causing viral infections
Answer: C. Helping in compost formation
29. Which example correctly represents a harmful effect of microorganisms?
A. Production of curd
B. Nitrogen fixation
C. Food spoilage by mould
D. Biogas generation
Answer: C. Food spoilage by mould
30. Which statement best explains why microorganisms can be described as both useful and harmful?
A. All microorganisms cause diseases
B. They participate in useful processes such as fermentation and decomposition, but some can spoil food or cause diseases
C. Microorganisms are useful only in water
D. All microorganisms are viruses
Answer: B. They participate in useful processes such as fermentation and decomposition, but some can spoil food or cause diseases
1. A round-bottom flask filled with water makes printed letters appear larger. In this situation, the flask behaves like a:
A. Mirror
B. Lens
C. Prism
D. Screen
Answer: B. Lens
2. Who introduced the term "cell" after examining cork under a microscope?
A. Antonie van Leeuwenhoek
B. Robert Hooke
C. Louis Pasteur
D. Robert Brown
Answer: B. Robert Hooke
3. Robert Hooke observed cork and gave the name "cells" to the small compartments he saw. These structures resembled:
A. Water droplets
B. Honeycomb-like compartments
C. Blood vessels
D. Plant roots
Answer: B. Honeycomb-like compartments
4. Which scientist is associated with the first observation of living cells?
A. Robert Hooke
B. Antonie van Leeuwenhoek
C. Robert Brown
D. Gregor Mendel
Answer: B. Antonie van Leeuwenhoek
5. Antonie van Leeuwenhoek is commonly referred as the:
A. Father of Genetics
B. Father of Microbiology
C. Father of Botany
D. Father of Cytology
Answer: B. Father of Microbiology
6. Which structure is present in a plant cell but not in an animal cell?
A. Cytoplasm
B. Nucleus
C. Cell membrane
D. Cell wall
Answer: D. Cell wall
7. The green pigment chlorophyll is found inside which plastid?
A. Chromoplast
B. Leucoplast
C. Chloroplast
D. Vacuole
Answer: C. Chloroplast
8. Chlorophyll is important because it helps in:
A. Digestion
B. Trapping sunlight for photosynthesis
C. Protein formation
D. Removing waste
Answer: B. Trapping sunlight for photosynthesis
9. The large vacuole of a plant cell mainly contributes to:
A. Storage and maintenance of cell shape
B. Production of chlorophyll
C. Control of all cell activities
D. Movement of the cell
Answer: A. Storage and maintenance of cell shape
10. Which cell is identified in the transcript as the longest cell in the human body?
A. Muscle cell
B. Red blood cell
C. Nerve cell
D. Bone cell
Answer: C. Nerve cell
11. Which of the following represents the correct order of organisation in a multicellular organism?
A. Cell $\rightarrow$ Organ $\rightarrow$ Tissue $\rightarrow$ Organ system $\rightarrow$ Organism
B. Tissue $\rightarrow$ Cell $\rightarrow$ Organ $\rightarrow$ Organism
C. Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system $\rightarrow$ Organism
D. Cell $\rightarrow$ Organ system $\rightarrow$ Tissue $\rightarrow$ Organism
Answer: C. Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system $\rightarrow$ Organism
12. Amoeba changes its body shape and moves with the help of:
A. Cilia
B. Flagella
C. Pseudopodia
D. Vacuoles
Answer: C. Pseudopodia
13. Which structure enables Paramecium to move through its surroundings?
A. Pseudopodia
B. Cilia
C. Roots
D. Cell wall
Answer: B. Cilia
14. Amoeba and Paramecium are both examples of:
A. Fungi
B. Bacteria
C. Protozoa
D. Algae
Answer: C. Protozoa
15. Bread mould belongs to which group of microorganisms?
A. Bacteria
B. Fungi
C. Protozoa
D. Viruses
Answer: B. Fungi
16. Which pair of microorganisms plays an important role in converting organic waste into natural manure?
A. Viruses and protozoa
B. Bacteria and fungi
C. Algae and viruses
D. Amoeba and Paramecium
Answer: B. Bacteria and fungi
17. Food items such as pickles and preserves remain usable for longer because salt or sugar:
A. Increases microbial growth
B. Reduces conditions favourable for microbial growth
C. Produces oxygen
D. Converts food into manure
Answer: B. Reduces conditions favourable for microbial growth
18. Which gas forms the main useful component of biogas according to the transcript?
A. Oxygen
B. Carbon dioxide
C. Methane
D. Nitrogen
Answer: C. Methane
19. During fermentation of dough, yeast releases which gas that helps the dough rise?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
Answer: B. Carbon dioxide
20. Bread becomes soft and fluffy mainly because:
A. Yeast absorbs all the water
B. Carbon dioxide is produced during fermentation
C. Nitrogen enters the dough
D. Oxygen freezes inside the dough
Answer: B. Carbon dioxide is produced during fermentation
21. Milk changes into curd due to the action of:
A. Rhizobium
B. Lactobacilli
C. Amoeba
D. Yeast
Answer: B. Lactobacilli
22. Lactobacilli convert the sugar present in milk into:
A. Methane
B. Lactic acid
C. Oxygen
D. Nitrogen
Answer: B. Lactic acid
23. Which bacterium is found in the root nodules of leguminous plants?
A. Lactobacillus
B. Rhizobium
C. Vibrio
D. Coccus
Answer: B. Rhizobium
24. Rhizobium is beneficial to plants mainly because it:
A. Produces chlorophyll
B. Carries out nitrogen fixation
C. Produces carbon dioxide
D. Causes fermentation
Answer: B. Carries out nitrogen fixation
25. The process in which atmospheric nitrogen is converted into a form useful for plants is called:
A. Fermentation
B. Photosynthesis
C. Biological nitrogen fixation
D. Respiration
Answer: C. Biological nitrogen fixation
26. Which group contributes significantly to oxygen production through photosynthesis according to the transcript?
A. Protozoa
B. Microalgae
C. Fungi
D. Viruses
Answer: B. Microalgae
27. Spirulina is classified in the transcript as a:
A. Fungus
B. Bacterium
C. Microalga
D. Protozoan
Answer: C. Microalga
28. According to the transcript, Spirulina is valued as a nutrient-rich source, particularly of:
A. Protein
B. Chlorine
C. Starch only
D. Carbon dioxide
Answer: A. Protein
29. The smallest basic unit from which living organisms are built is the:
A. Tissue
B. Organ
C. Cell
D. Organ system
Answer: C. Cell
30. Which structure is not present as a well-defined structure in bacterial cells?
A. Cell wall
B. Cytoplasm
C. Cell membrane
D. Well-defined nucleus
Answer: D. Well-defined nucleus
31. Instead of a well-defined nucleus, bacterial cells contain a:
A. Chloroplast
B. Nucleoid
C. Vacuole
D. Nuclear membrane
Answer: B. Nucleoid
32. Vegetable waste and dried leaves can be converted into compost mainly through the action of:
A. Microorganisms
B. Red blood cells
C. Nerve cells
D. Viruses only
Answer: A. Microorganisms
33. Which gas can be identified when lime water turns milky during an experiment involving yeast?
A. Oxygen
B. Hydrogen
C. Carbon dioxide
D. Nitrogen
Answer: C. Carbon dioxide
34. Which part of a cell acts as its control centre?
A. Cell membrane
B. Cytoplasm
C. Nucleus
D. Vacuole
Answer: C. Nucleus
35. The nucleus is important because it:
A. Only stores water
B. Controls cellular activities and contains genetic information
C. Forms pseudopodia
D. Produces mould
Answer: B. Controls cellular activities and contains genetic information
36. A jelly-like substance located between the cell membrane and nucleus is called:
A. Cytoplasm
B. Cell wall
C. Nucleoid
D. Chlorophyll
Answer: A. Cytoplasm
37. A student observes a microorganism with an irregular shape that uses temporary projections for movement and capturing food. The organism is most likely:
A. Paramecium
B. Amoeba
C. Bread mould
D. Rhizobium
Answer: B. Amoeba
38. A farmer grows beans and notices swollen structures on their roots. These structures are important because they contain bacteria involved in:
A. Fermentation
B. Nitrogen fixation
C. Photosynthesis
D. Food preservation
Answer: B. Nitrogen fixation
39. If salt or sugar is added in sufficient quantity to a food product, the growth of many microorganisms is reduced mainly because:
A. Conditions become less favourable for their growth
B. Microorganisms become larger
C. Chlorophyll is destroyed
D. Nitrogen fixation begins
Answer: A. Conditions become less favourable for their growth
40. Which statement correctly matches an organism or microorganism with its role?
A. Amoeba — movement by cilia
B. Paramecium — movement by pseudopodia
C. Rhizobium — nitrogen fixation
D. Lactobacillus — production of methane
Answer: C. Rhizobium — nitrogen fixation
1. What is the basic structural and functional unit of a living organism?
Answer: The cell.
2. Who gave the term "cell" after observing cork?
Answer: Robert Hooke.
3. Which scientist is associated with the first observation of living cells mentioned in the transcript?
Answer: Antonie van Leeuwenhoek.
4. Which structure controls the activities of a cell?
Answer: The nucleus.
5. Name the jelly-like material present inside a cell.
Answer: Cytoplasm.
6. Which structure is found in plant cells but absent in animal cells?
Answer: Cell wall.
7. Which organelle contains chlorophyll?
Answer: Chloroplast.
8. What is the main function of chlorophyll?
Answer: It traps light energy for photosynthesis.
9. Which cell is considered the longest cell in the human body?
Answer: Nerve cell.
10. What are pseudopodia?
Answer: Temporary projections used by Amoeba for movement and feeding.
11. Which structures help Paramecium in locomotion?
Answer: Cilia.
12. To which group do Amoeba and Paramecium belong?
Answer: Protozoa.
13. Bread mould belongs to which group of microorganisms?
Answer: Fungi.
14. Name the gas mainly responsible for the fuel value of biogas.
Answer: Methane.
15. Which microorganism is used in the preparation of bread?
Answer: Yeast.
16. Which gas causes bread dough to rise?
Answer: Carbon dioxide.
17. Which bacterium converts milk into curd?
Answer: Lactobacillus.
18. Which acid is produced during the conversion of milk into curd?
Answer: Lactic acid.
19. Which bacterium is commonly present in the root nodules of leguminous plants?
Answer: Rhizobium.
20. What is the process of converting atmospheric nitrogen into a usable form called?
Answer: Nitrogen fixation.
21. Which microorganisms help in the decomposition of organic waste to form compost?
Answer: Bacteria and fungi.
22. Which microorganism mentioned in the transcript is a nutrient-rich microalga?
Answer: Spirulina.
23. What is the region containing genetic material in a bacterial cell called?
Answer: Nucleoid.
24. Why do salt and sugar help preserve food?
Answer: They make conditions less favourable for microbial growth.
25. Arrange the following in the correct order: organ, cell, tissue, organ system.
Answer: Cell $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organ system.
1. Why is the cell called the basic unit of life?
Answer:
A cell is called the basic structural and functional unit of life because living organisms are made up of cells, and essential life processes take place within cells.
2. State two differences between a plant cell and an animal cell.
Answer:
- Plant cells have a cell wall, whereas animal cells do not.
- Plant cells contain chloroplasts, whereas animal cells generally do not.
3. How do Amoeba and Paramecium differ in their mode of movement?
Answer:
Amoeba moves with the help of pseudopodia, whereas Paramecium moves using numerous tiny hair-like structures called cilia.
4. Explain how yeast helps in making bread soft and fluffy.
Answer:
Yeast carries out fermentation and produces carbon dioxide. The gas gets trapped in the dough, causing it to expand and become soft and fluffy.
5. How does Lactobacillus convert milk into curd?
Answer:
Lactobacillus converts the sugar present in milk into lactic acid. This causes changes in the milk and leads to the formation of curd.
6. Explain the importance of Rhizobium to leguminous plants.
Answer:
Rhizobium lives in the root nodules of leguminous plants and helps convert atmospheric nitrogen into forms that can be utilised by plants. Thus, it helps improve nitrogen availability in the soil.
7. How do microorganisms contribute to compost formation?
Answer:
Microorganisms such as bacteria and fungi decompose biodegradable organic waste. This decomposition converts the waste into compost or natural manure.
8. Why are microalgae important in aquatic ecosystems?
Answer:
Microalgae carry out photosynthesis and contribute to oxygen production. They also act as an important source of food in aquatic ecosystems.
9. Explain why food preservation using salt or sugar reduces spoilage.
Answer:
A sufficient amount of salt or sugar creates conditions that are less suitable for the growth of many microorganisms. As a result, food spoilage is reduced.
10. How is biogas related to waste management?
Answer:
Organic waste can be decomposed by microorganisms to produce biogas. Thus, waste is converted into a useful fuel while also helping in waste management.
1. Identifying an Unknown Microorganism
A student observes a microscopic organism that has an irregular shape. It forms temporary extensions of its body, which help it move and capture food.
a. Identify the organism.
Answer: Amoeba.
b. Name the structures used for movement.
Answer: Pseudopodia.
c. Why are these structures called temporary projections?
Answer: They are formed as needed and can change their position and shape.
2. Bread Mould Investigation
Two pieces of bread are kept under different conditions.
- Bread A is kept moist in a warm place.
- Bread B is kept dry in a cooler place.
After several days, mould appears more rapidly on Bread A.
a. Which group of microorganisms is responsible for the mould?
Answer: Fungi.
b. What conditions favoured faster mould growth on Bread A?
Answer: Moist and warm conditions.
c. What conclusion can be drawn from this investigation?
Answer: Moisture and suitable warmth favour the growth of mould.
3. Making Curd at Home
Milk is mixed with a small amount of curd and kept under suitable conditions. After some time, the milk changes into curd.
a. Which microorganism is mainly responsible for this change?
Answer: Lactobacillus.
b. What substance is produced during this process?
Answer: Lactic acid.
c. Why does this process change the properties of milk?
Answer: The production of lactic acid causes the milk to undergo changes and form curd.
4. Nitrogen-Rich Soil
A farmer grows pea plants in a field. After some time, swollen nodules are observed on their roots.
a. Which microorganism is likely to be present in these nodules?
Answer: Rhizobium.
b. What important process does this microorganism perform?
Answer: Nitrogen fixation.
c. How does this association benefit the plant?
Answer: It helps make nitrogen available in a form that can be utilised by the plant.
5. The Rising Dough
A baker adds yeast to flour and water while preparing dough. After some time, the dough increases in volume.
a. Which process is taking place?
Answer: Fermentation.
b. Which gas is produced?
Answer: Carbon dioxide.
c. How does this gas help in making bread?
Answer: The gas causes the dough to expand, producing a soft and fluffy texture.
6. Food Preservation Problem
Two samples of fruit are stored under similar conditions. One sample is converted into a sweet preserve containing a high concentration of sugar, while the other is left untreated. The untreated sample spoils earlier.
a. Why does the untreated sample spoil faster?
Answer: Microorganisms can grow more easily on it.
b. How does sugar help preserve the other sample?
Answer: It makes conditions less favourable for the growth of many microorganisms.
c. Name one other substance mentioned in the transcript that can be used for food preservation.
Answer: Salt.
7. Composting Organic Waste
A school collects vegetable peels and dried leaves and places them in a compost pit. After several weeks, the waste changes into a dark, soil-like material.
a. What is the final product called?
Answer: Compost.
b. Which organisms are mainly responsible for this change?
Answer: Microorganisms such as bacteria and fungi.
c. Why is this process useful?
Answer: It converts biodegradable waste into useful natural manure.
8. Comparing Plant and Animal Cells
A student observes two cells under a microscope. Cell X has a cell wall and chloroplasts, whereas Cell Y lacks both structures.
a. Identify Cell X and Cell Y.
Answer: Cell X is a plant cell, and Cell Y is an animal cell.
b. What is the role of chlorophyll present in Cell X?
Answer: It helps trap light energy for photosynthesis.
c. Which additional structure in Cell X helps provide rigidity and support?
Answer: Cell wall.
9. Movement of Unicellular Organisms
Two students observe different microorganisms.
- Organism P moves by changing its body shape.
- Organism Q moves using numerous tiny hair-like structures.
a. Identify Organism P.
Answer: Amoeba.
b. Identify Organism Q.
Answer: Paramecium.
c. Name their respective locomotory structures.
Answer: Amoeba uses pseudopodia, while Paramecium uses cilia.
10. Waste-to-Energy System
A village collects biodegradable waste and processes it in a biogas plant. A useful gas is produced and used as a fuel.
a. Which microorganisms are involved in the decomposition of organic matter?
Answer: Microorganisms involved in decomposition.
b. Name the main useful gas associated with biogas.
Answer: Methane.
c. State one environmental benefit of this system.
Answer: It helps manage organic waste by converting it into a useful fuel.