NCERT Solutions for Class 7 Science Chapter 8

1. Reproduction in Plants The chapter Reproduction in Plants explores how plants create new offspring, ensuring the continuation of their species. Here’s a breakdown of the key concepts: Two Main Methods: ● Sexual Reproduction: This involves the fusion of male and female gametes (sex cells) to form a zygote, which develops into a new plant. ○ Flower Parts: Flowers are the reproductive organs of plants, containing male (stamen) and female (pistil) parts. ○ Pollination: Transfer of pollen (male gametes) from the stamen to the stigma (female part) of a flower (can be wind, insect, or animal-mediated). ○ Fertilization: Fusion of pollen grain (sperm) with the ovule (egg) in the ovary, forming a zygote. ○ Seed Formation: The fertilized ovule develops into a seed containing an embryo (new plant) and a seed coat for protection. ● Asexual Reproduction: This involves producing new plants without involving fertilization. ○ Common Methods: Examples include vegetative propagation (using plant parts like cuttings), budding, and spore formation. Key Points: ● Sexual reproduction allows for genetic variation in offspring, which is crucial for adaptation and survival in changing environments. ● Asexual reproduction is generally faster but produces offspring that are genetically identical to the parent plant. ● Flowers play a vital role in sexual reproduction by attracting pollinators and facilitating fertilization. ● Seeds are essential for dispersal and dormancy (resting stage) in plants. Learning about Plant Reproduction Helps Us Understand:

2. ● How plants ensure the continuation of their species. ● The importance of flowers and pollination. ● The difference between sexual and asexual reproduction in plants. ● The role of seeds in plant dispersal and survival. NCERT Solutions for Class 7 Science Chapter 8: Reproduction in Plants Exercises 1.Fill in the blanks: (a) Production of new individuals from the vegetative part of parent is called ___________. (b) A flower may have either male or female reproductive parts. Such a flower is called _______. (c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as __________. (d) The fusion of male and female gametes is termed as ____________ . (e) Seed dispersal takes place by means of ________ and __________. Ans : (a) vegetative propagation. (b) unisexual. (c) pollination. (d) fertilization.

3. (e) wind and animals. 2. Describe the different methods of asexual reproduction. Give examples. Ans : 1. Vegetative Propagation: This method involves using vegetative parts (non-flowering) of a plant to grow a new plant that’s genetically identical to the parent. ● Examples: ○ Cutting: Taking a stem or leaf cutting and planting it in a suitable medium (soil, water) to develop roots and form a new plant (e.g., rose cuttings, money plant leaves). ○ Layering: Bending a stem of a plant towards the ground, burying a portion under soil, and allowing it to develop roots before separating it from the parent plant (e.g., some climbing plants). ○ Corms and Tubers: Underground storage organs like corms (crocus) and tubers (potato) can sprout and grow into new plants. 2. Budding: A new plant grows as an outgrowth (bud) on the parent plant. This bud eventually detaches and becomes an independent plant. ● Example: Bryophyllum (mother of thousands) plants develop small plantlets along the edges of their leaves, which can fall off and grow into new individuals. 3. Spore Formation: Some plants like ferns and mosses reproduce by producing spores. These spores are haploid (having only one set of chromosomes) and can germinate

4. under favorable conditions to develop into a gametophyte (sex organs producer). The gametophytes then produce gametes (eggs and sperm) that fuse to form a diploid zygote, which grows into a new sporophyte (spore producer). 3. Explain what you understand by sexual reproduction. Ans : Sexual reproduction in plants is like mixing and matching! Here’s the gist: 1.Flowers: They have both boy parts (pollen) and girl parts (eggs). 2.Pollination: Pollen moves from boy to girl parts (wind, insects, etc.). 3.Fertilization: Boy and girl parts fuse, creating a seed (baby plant). 4.Seed Spreads: Seed travels and finds a new spot to grow. 4. State the main difference between asexual and sexual reproduction. Ans Feature Asexual Reproduction Sexual Reproduction Process New plant grows from a single parent without fertilization Requires fusion of male (pollen) and female (egg) gametes Genetic Makeup Offspring are genetically identical to the parent Offspring have a mix of genes from both parents (genetic variation) Speed Generally faster Typically slower Examples Vegetative propagation (cuttings, layering), budding, spores Pollination, fertilization, seed development

5. Benefits Faster, ensures desired traits are passed on Genetic variation allows for adaptation and evolution Drawbacks Limited genetic variation, susceptible to same diseases as parent Slower, relies on external factors for successful reproduction 5.Sketch the reproductive parts of a flower.. Ans : 6.Explain the difference between self-pollination and cross-pollination Ans : Feature Self-Pollination Cross-Pollination

6. Pollen Source Same flower or same plant Different plant of the same species Transfer Mechanism Direct transfer within the flower or by wind within a closed flower Wind, insects, animals, or water Genetic Variation Low (clones) High Examples Peas, beans, some orchids, wheat Roses, sunflowers, most fruits and vegetables 7.How does the process of fertilization take place in flowers? Ans : Pollen (sperm) races down a long tube from the flower’s boy parts (stamen) to the girl parts (ovary). There, it meets an egg cell, and bingo! Fertilization happens, creating a seed (baby plant) that the flower develops into a fruit (taxi) to travel and find a new home to grow. 8.Describe the various ways by which seeds are dispersed. Ans : Seeds don’t have legs to travel! But plants have developed clever ways to ensure their offspring spread far and wide. Here’s a look at some seed dispersal methods: 1.Wind Dispersal: Many seeds are lightweight and have features like wings, parachutes, or hairs that help them catch the wind and travel long distances. Examples: dandelion, maple, milkweed. 2.Animal Dispersal: Some seeds have hooks, barbs, or sticky surfaces that cling to animal fur or feathers. As animals move around, they carry the seeds to new locations. Examples: burdock, cocklebur, mistletoe. 3.Water Dispersal: Seeds with waterproof coats or buoyant structures can travel by water currents or float on the surface, reaching new areas. Examples: coconut, lotus, mangrove. 4.Explosive Dispersal: Certain plants like squirting cucumber and witch hazel have pods that dry out and explode, forcefully ejecting seeds in all directions.

7. 5.Gravity Dispersal: Heavy seeds or fruits simply fall from the parent plant and may roll or bounce a short distance. Examples: acorns, walnuts, cherries. 9.Match items in Column I with those in Column II Column I Column II Bud Maple Eyes Spirogya Fragmentation Yeast Wings Bread mould Spores Potato Rose Ans : Column I Column II Bud Yeast Eyes Potato Fragmentation Spirogya Wings Maple Spores Bread mould

8. 10. Tick (%/) the correct answer: (a) The reproductive part of a plant is the (i) leaf (ii) stem (iii) root (iv) flower (b) The process of fusion of the male and the female gametes is called (i) fertilisation (ii) pollination (iii) reproduction (iv) seed formation c) Mature ovary forms the (i) seed (ii) stamen (iii) pistil (iv) fruit (d) A spore producing plant is (i) rose (ii) bread mould (iii) potato (iv) ginger (e) Bryophyllum can be reproduced by its (i) stem (ii) leaves (iii) roots (iv) flower Ans : (a) (iv) flower (b) (i) fertilisation (c) (i) seed (d) (ii) bread mould (e) (ii) leaves