Hello students, in this blog you can find important summary notes from the Chapter 12, Science , NCERT Book of Class 7. These notes can be used for preparation of various school Competitive Exams, Olympiads and also developing Fundamentals.
Reproduction in Plants
– The production of new individuals from their parents is known as reproduction.
Reproduction in Plants:
– Flowers perform the function of reproduction in plants. Flowers are the reproductive parts.
– There are several ways by which plants produce their offspring. These modes
are categorized into two types:
1. Asexual reproduction : plants can give e rise to new plants without seeds,
2. Sexual reproduction : new plants are obtained from seeds.
1. Asexual Reproduction in Plants:
1.1 Vegetative propagation : It is a type of asexual reproduction in which new plants are produced from roots, stems, leaves and buds. Since reproduction is through the vegetative parts of the plant, it is known as vegetative propagation.
Examples: champa, rose, money plant
– 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, as they are produced from a single parent.
1.2 Budding :
– The bud gradually grows and gets detached from the parent cell and forms a new yeast cell.
1.3 Fragmentation :
– An alga breaks up into two or more fragments. These fragments or pieces grow into new individuals.
1.4 Spore formation :
– Spores are asexual reproductive bodies.
– Under favourable conditions, a spore germinates and develops into a new individual.
– Examples : Plants such as moss and .
ferns also reproduce by means of spores.
2. Sexual Reproduction in Plants:
– Plants produced by sexual reproduction have characters of both the parents.
– Plants produce seeds as a result of sexual reproduction.
– Stamens are the male reproductive part and pistil is the female reproductive part of a plant
– Flowers which contain either only pistil or only stamens are called unisexual flowers.
– Flowers which contain both stamens and pistil are called bisexual flowers.
– Examples: Corn, papaya and cucumber produce unisexual flowers, whereas mustard, rose and petunia have bisexual flowers.
– Anther contains pollen grains which produce male gametes.
– Pistil consists of stigma, style and ovary.
– Ovary contains one or more ovules. The female gamete or the egg is formed in an ovule.
– In sexual reproduction a male and a female gamete fuse to form a zygote.
2.1 Pollination :
– Generally, pollen grains have a tough protective coat which prevents them from drying up.
– Since pollen grains are light, they can be carried by wind or water.
– The transfer of pollen from the anther to the stigma of a flower is called pollination.
– If the pollen lands on the stigma of the .
same flower or another flower of the same plant, it is called self-pollination.
– When the pollen of a flower lands on the stigma of a flower of different plant of the same kind, it is called cross-pollination.
2.2 Fertilisation :
– The cell which results after fusion of the gametes is called a zygote.
– The process of fusion of male and female gametes (to form a zygote) is called fertilisation.
– The zygote develops into an embryo.
3. Fruits and seed formation :
– After fertilisation, the ovary grows into a fruit and other parts of the flower fall off.
– The fruit is the ripened ovary. The seeds develop from the ovules.
– The seed contains an embryo enclosed in a protective seed coat.
– Some fruits are fleshy and juicy such as mango and orange. Some fruits are hard like almonds and walnuts.
Question & Answers
1. Fill in the blanks:
(a) Production of new individuals from the vegetative o part of parent is called _____.
(b) A flower may have either male or a 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 g place by means of ________ , ________ and ___________.
Answers: (a) vegetative propagation; (b) unisexual; (c) pollination; (d) fertilisation; (e) wind, water, animals