- Production of new individuals from their parents is known as reproduction
Parts of a plant
- Vegetative part (roots, stems and leaves)
- Reproductive part (flowers)
Type of reproduction
- Asexual reproduction – plants give rise to new plants without seeds
- Sexual reproduction – new plants are obtained from seeds
- Reproduction is through the vegetative parts of the plant (roots, stem, leaf or bud)
- Thus it is known as vegetative propagation.
- Eg: Stem cutting of rose, Buds in the margins of leaves of Bryophyllum, Roots of sweet potato
- Plants produced by vegetative propagation take less time to grow and bear flowers and fruits earlier than those produced from seeds
- The new plants are exact copies of the parent plant
- The small bulb-like projection coming out from the yeast cell is called a bud
- The bud gradually grows and gets detached from the parent cell and forms a new yeast cell
- An alga breaks up into two or more fragments.
- These fragments or pieces grow into new individuals
- When water and nutrients are available algae grow and multiply rapidly by fragmentation
- The spores are asexual reproductive bodies.
- Each spore is covered by a hard protective coat to withstand unfavourable conditions such as high temperature and low humidity.
- Under favourable conditions, a spore germinates and develops into a new individual.
- Plants such as moss and ferns reproduce by means of spores
Reproduction involving the fusion of a male and a female gamete
- Flowers having both stamens (male reproductive part) and pistil (female reproductive part), are called bisexual flowers
- Flowers having only one, either male or female parts are unisexual flowers
- Anther contains pollen grains which produce male gametes
- The egg/female gamete is formed in the ovule
- The transfer of pollen from the anther to the stigma of a flower is called pollination
- Pollen grains have a tough protective coat which prevents them from drying up.
- They get carried by wind, water or even insects
- If the pollen lands on the stigma of the same flower
- If the pollen of a flower lands on the stigma of another flower of the same plant, or that of a different plant of the same kind
- The male and female gamete fuse to form the zygote
- The process of fusion of male and female gametes (to form a zygote) is called fertilisation
- The zygote develops into an embryo.
Fruit and seed formation
- After fertilisation, the ovary grows into the fruit and other parts of the flower fall off.
- The seeds develop from the ovules.
- The seed contains an embryo enclosed in a protective seed coat.
- Seeds are dispersed by wind, water, animals and even humans
- Seed dispersal helps the plants to
- Prevent overcrowding,
- Avoid competition for sunlight, water and minerals
- Invade new habitats