Quiz Class 7th Science 15-05-2026

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Q1. Vegetative Propagation in Potato Takes Place Through Stem/Eye

Description

The correct answer is Stem / Eye. Potato reproduces through vegetative propagation with the help of small structures called “eyes” present on its surface. These eyes are actually buds found on the underground stem of the potato. Because potato stores food and contains buds, it is considered a modified stem and not a root.

Vegetative propagation is a type of asexual reproduction in which new plants grow from parts of the parent plant such as stem, root, or leaves instead of seeds. In potato plants, every eye has the ability to grow into a completely new potato plant under suitable conditions.

Detailed Explanation

Potato is one of the most common examples of vegetative propagation through stem. Farmers often cut potatoes into several pieces before planting them in soil. Each piece must contain at least one eye. These eyes contain inactive buds that start growing when they receive moisture, air, and warmth from the environment.

After planting, the eye begins to form shoots upward and roots downward. Gradually, a new potato plant develops. This method is very useful because it produces plants quickly and the new plants remain genetically similar to the parent plant.

Vegetative propagation is widely used in agriculture because it saves time and gives faster results compared to seed germination. It also helps preserve the qualities of the original plant, such as size, taste, and productivity.

How Eyes Develop into Plants

The eye of the potato contains living cells capable of division. When the potato piece is placed in soil, these cells become active. The bud starts using stored food present inside the potato for growth. First, a small shoot appears above the soil surface. Then roots begin to spread into the soil to absorb water and minerals.

As the plant grows, leaves begin photosynthesis and prepare food. Eventually, new underground stems swell and form new potatoes. In this way, one potato can produce many new potatoes.

Advantages of Potato Vegetative Propagation

1. Fast reproduction of plants.
2. New plants are similar to parent plant.
3. Useful for large-scale farming.
4. No need for seeds.
5. Higher survival rate.

Disadvantages

1. Diseases can spread from parent plant to new plants.
2. Less genetic variation.
3. Plants may become weaker over many generations.

Step-by-Step Understanding

Step 1: Potato contains eyes or buds.
Step 2: Potato pieces are planted in soil.
Step 3: Buds receive water and warmth.
Step 4: Shoots and roots develop.
Step 5: A new potato plant grows.

Real-Life Examples

1. Farmers growing potatoes in fields.
2. Home gardeners using potato eyes for planting.

Key Points

• Potato reproduces through eyes.
• Eyes are buds on underground stem.
• Example of vegetative propagation.
• New plants resemble parent plant.
• Fast and useful agricultural method.

Q2. Bryophyllum Reproduces Through Leaves

Description

The correct answer is Leaves. Bryophyllum is a special plant that reproduces vegetatively through leaves. Small buds grow along the edges of its leaves, and these buds develop into tiny plantlets.

When these plantlets fall onto moist soil, they start growing independently and form new Bryophyllum plants. This type of reproduction is an example of vegetative propagation through leaves.

Detailed Explanation

Bryophyllum is known for its remarkable ability to produce new plants directly from its leaf margins. The leaf contains special tissues capable of forming roots and shoots. Tiny buds appear naturally on the sides of mature leaves. These buds grow slowly into miniature plants while still attached to the parent leaf.

After becoming mature, the tiny plantlets detach from the leaf and fall onto the ground. If the soil is moist and conditions are favorable, the plantlets develop roots and grow into complete plants.

This method of reproduction allows Bryophyllum to spread quickly without seeds. Even a single leaf can produce many new plants. This ability helps the plant survive and multiply easily in nature.

Importance of Bryophyllum Reproduction

Bryophyllum demonstrates that plants can reproduce from vegetative parts. It also shows the amazing regenerative power of plant tissues.

Scientists and gardeners study such plants to understand plant growth and cloning techniques. This method is useful because it produces plants identical to the parent.

Conditions Needed

• Moist soil
• Sunlight
• Suitable temperature
• Healthy leaves

Advantages

1. Fast multiplication.
2. No need for flowers or seeds.
3. New plants grow quickly.
4. Plants remain genetically identical.

Step-by-Step Understanding

Step 1: Buds form on leaf margins.
Step 2: Buds develop into tiny plantlets.
Step 3: Plantlets form roots and shoots.
Step 4: Plantlets detach from leaf.
Step 5: New Bryophyllum plants grow in soil.

Real-Life Examples

1. Bryophyllum growing in gardens.
2. Leaf propagation seen in some ornamental plants.

Key Points

• Bryophyllum reproduces through leaves.
• Buds grow on leaf margins.
• Example of vegetative propagation.
• Plantlets grow into new plants.
• No seeds are required.

Q3. Yeast Reproduces by Budding

Description

The correct answer is Budding. Yeast is a microscopic unicellular organism that reproduces asexually by budding. In this method, a small outgrowth develops from the parent cell and gradually becomes a new yeast cell.

Yeast is very important in industries because it helps in fermentation and baking processes.

Detailed Explanation

Budding begins when a tiny projection appears on the surface of the parent yeast cell. This projection is called a bud. Inside the parent cell, the nucleus divides into two parts through cell division.

One nucleus moves into the growing bud. The bud continues increasing in size while receiving nutrients from the parent cell. After reaching maturity, the bud separates and becomes an independent yeast organism.

Sometimes buds may remain attached temporarily and form chains of yeast cells.

Importance of Yeast

Yeast plays a major role in food industries. It converts sugar into alcohol and carbon dioxide during respiration.

In bread making, carbon dioxide produced by yeast causes dough to rise and become soft. Yeast is also used in making cakes, pastries, beer, and wine.

Conditions Needed for Growth

• Warm environment
• Moisture
• Sugar or food source
• Suitable temperature

Advantages of Budding

1. Fast reproduction.
2. Simple process.
3. No mating required.
4. Large number of offspring produced quickly.

Step-by-Step Understanding

Step 1: Small bud forms on yeast cell.
Step 2: Nucleus divides into two parts.
Step 3: One nucleus enters the bud.
Step 4: Bud grows larger.
Step 5: New yeast cell separates.

Real-Life Examples

1. Bread preparation.
2. Alcohol production industries.

Key Points

• Yeast reproduces by budding.
• Bud develops from parent cell.
• Used in fermentation.
• Produces carbon dioxide.
• Important industrial microorganism.

Q4. Spirogyra Reproduces by Fragmentation

Description

The correct answer is Fragmentation. Spirogyra is a filamentous green alga that reproduces asexually through fragmentation.

In fragmentation, the body breaks into smaller pieces called fragments. Each fragment grows into a complete new organism.

Easy Explanation

Spirogyra looks like long green threads in water. When these threads break into smaller pieces, each piece can grow into a new Spirogyra.

Why Fragmentation Happens

• Water movement
• External force
• Natural breaking of filaments

Step-by-Step Understanding

Step 1: Spirogyra forms long filaments.
Step 2: Filament breaks into fragments.
Step 3: Each fragment remains alive.
Step 4: Fragments continue growing.
Step 5: New Spirogyra organisms form.

Advantages of Fragmentation

1. Simple method of reproduction.
2. Rapid increase in number.
3. No need for seeds or spores.

Examples

1. Spirogyra in ponds.
2. Some algae reproduce similarly.

Key Points

• Spirogyra reproduces by fragmentation.
• Body breaks into smaller parts.
• Each fragment forms a new organism.
• Common in algae.
• Simple asexual reproduction method.

Q5. Bread Mould is a Spore Producing Plant

Description

The correct answer is Bread mould. Bread mould reproduces by forming spores. Spores are tiny reproductive structures that can grow into new organisms under suitable conditions.

Bread mould commonly grows on moist bread and appears as black or green patches.

Easy Explanation

Spores are very light and can spread through air. When they land on moist surfaces, they grow into new bread mould.

Structure of Bread Mould

Bread mould contains:

• Hyphae (thread-like structures)
• Sporangium (spore-producing structure)

Spores are formed inside the sporangium.

Step-by-Step Understanding

Step 1: Bread mould grows on moist bread.
Step 2: Sporangia develop on tips.
Step 3: Spores form inside sporangia.
Step 4: Sporangia burst open.
Step 5: Spores spread and form new mould.

Conditions Required for Spore Germination

• Moisture
• Warm temperature
• Food source

Advantages of Spore Formation

1. Large number of spores produced.
2. Easy dispersal by air.
3. Helps survival in unfavorable conditions.

Examples

1. Bread mould on stale bread.
2. Fungi reproducing through spores.

Key Points

• Bread mould reproduces by spores.
• Spores spread through air.
• Moist conditions help growth.
• Example of asexual reproduction.
• Common in fungi.

Quick Revision Notes

Potato

• Reproduces through eyes.
• Eyes are buds on underground stem.
• Example of vegetative propagation.

Bryophyllum

• Reproduces through leaves.
• Plantlets grow on leaf margins.
• No seeds required.

Yeast

• Reproduces by budding.
• New bud develops from parent cell.
• Important in baking and fermentation.

Spirogyra

• Reproduces by fragmentation.
• Broken fragments form new organisms.
• Common aquatic algae.

Bread Mould

• Reproduces through spores.
• Spores spread in air.
• Grows on moist food materials.