How do Organisms Reproduce — Previous Year Questions (Class 10 Science)
Reproduction is a fundamental life process enabling organisms to create new individuals. This chapter explores asexual and sexual reproduction in plants an
TL;DR: Reproduction is a fundamental life process enabling organisms to create new individuals. This chapter explores asexual and sexual reproduction in plan…
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Reproduction is a fundamental life process enabling organisms to create new individuals. This chapter explores asexual and sexual reproduction in plants an
How do Organisms Reproduce — Previous Year Questions with Solutions
Q (2023, 3 marks): Explain the difference between asexual and sexual reproduction. Give two examples of each.
Answer: Difference Between Asexual and Sexual Reproduction:
Asexual Reproduction:
1. Involves single parent
2. No gamete formation
3. Offspring genetically identical to parent (clone)
4. Produces offspring quickly
5. Examples: Budding in Hydra, Binary fission in bacteria
Sexual Reproduction:
1. Involves two parents
2. Fusion of male and female gametes
3. Offspring genetically different (variation)
4. Slower process, takes more time
5. Examples: Reproduction in humans, flowering plants
Q (2022, 4 marks): Describe the process of vegetative reproduction in plants. Give three examples.
Answer: Vegetative Reproduction in Plants:
Definition - Asexual reproduction in plants producing offspring from vegetative parts without seeds.
Process:
1. Occurs through stems, roots, leaves, tubers, or bulbs
2. No flowering or seed formation
3. Creates genetically identical offspring
4. Faster and more efficient than sexual reproduction
Examples with processes:
1. Potato - Underground tubers develop buds that grow into new plants
2. Onion - Bulbs separate and each develops into new plant
3. Strawberry - Runners grow horizontally, develop nodes with roots, form new plants
4. Ginger - Rhizomes (underground stems) fragment and each piece grows into new plant
5. Bryophyllum - Leaves develop plantlets at margins that fall and grow
Benefits:
- Faster reproduction
- Genetic uniformity
- No dependence on pollination
Q (2021, 5 marks): Explain the structure and function of a flower in sexual reproduction of plants.
Answer: Structure and Function of Flower in Sexual Reproduction:
Floral Parts and Functions:
1. Sepals:
- Protect flower bud
- Green leaf-like structures
2. Petals:
- Attract pollinators
- Usually brightly colored
3. Stamens (Male parts):
- Produce pollen (male gamete)
- Consist of anther and filament
- Anther contains pollen sacs
4. Carpel (Female part):
- Receives pollen
- Contains ovule with egg cell
- Consists of stigma, style, and ovary
Sexual Reproduction Process:
1. Pollination - Pollen transferred to stigma
2. Pollen tube growth - Extends down style to ovule
3. Fertilization - Male gamete fuses with egg cell
4. Seed development - Ovule develops into seed
5. Fruit formation - Ovary develops into fruit
Q (2023, 4 marks): Describe the life cycle of a frog. How does it differ from human reproduction?
Answer: Frog Life Cycle (Metamorphosis):
1. Egg - Laid in water in clusters (spawn)
2. Tadpole - Aquatic larva with:
- Tail for swimming
- External gills for respiration
- Feeds on algae
3. Metamorphosis stages:
- Hind legs develop
- Front legs appear
- Tail shortens
- Lungs develop, gills disappear
- Feeding changes to insects
4. Adult Frog - Land and water life
Differences from Human Reproduction:
1. Frogs: External fertilization (in water), Humans: Internal fertilization
2. Frogs: Many eggs (hundreds), Humans: Few eggs (monthly)
3. Frogs: Aquatic larval stage, Humans: Terrestrial development in womb
4. Frogs: Metamorphosis (body transformation), Humans: Continuous development
5. Frogs: No parental care usually, Humans: Extended parental care
6. Development time - Frogs: weeks to months, Humans: 9 months
Q (2022, 3 marks): What is budding? Explain budding in Hydra with a diagram description.
Answer: Budding:
Definition - Form of asexual reproduction where new organism develops as outgrowth from parent.
Budding in Hydra:
1. Parent Hydra - Cylindrical body with tentacles
2. Bud formation:
- Small projection appears on body wall
- Cells divide and develop
- Bud enlarges, develops tentacles
3. Detachment:
- When mature, bud develops mouth and separates
- Becomes independent Hydra
4. Result: Clone of parent with all parent's characteristics
Key Features:
1. Asexual reproduction (single parent)
2. Rapid multiplication
3. Identical offspring
4. Efficient in favorable conditions
5. Occurs in Hydra, corals, yeast
Q (2021, 3 marks): Explain the process of binary fission in bacteria with steps.
Answer: Binary Fission in Bacteria:
Definition - Asexual reproduction where bacterial cell divides into two identical daughter cells.
Steps:
1. DNA Replication:
- Circular DNA attaches to cell membrane
- DNA unwinds and replicates
- Two identical DNA copies formed
2. Cell Elongation:
- Cell grows and elongates
- Two DNA copies move to opposite poles
3. Septum Formation:
- New cell membrane grows inward
- Cell wall material deposited
- Creates dividing wall (septum)
4. Cell Separation:
- Two daughter cells separate
- Each has identical DNA
- Both capable of independent growth
Characteristics:
1. Very rapid (E.coli every 20 minutes)
2. Produces identical clones
3. Asexual process
4. Allows rapid population growth
Frequently Asked Questions
What is the significance of variation in sexual reproduction?
Variation in sexual reproduction creates genetic diversity, which enables organisms to adapt to changing environments and increases species survival chances.
Why is vegetative reproduction preferred by farmers for certain crops?
Farmers prefer vegetative reproduction because it produces genetically identical, disease-free plants with desirable traits, and provides faster multiplication than seed production.
More Class 10 Science PYQs
- Chemical Reactions and Equations
- Light (Reflection and Refraction)
- Electricity
- Acids, Bases and Salts
- Metals and Non-metals
- Life Processes
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