12.
REPRODUCTION IN PLANTS
1) What are the different modes of reproduction in plants? Explain with
examples.
A) The modes of reproduction in plants are broadly classified into two
categories.
• Asexual reproduction
• Sexual reproduction
Asexual reproduction: in this type of reproduction, the plant reproduces
without the involvement of seeds. the new individual is produced from a
single parent. Plants adopt different methods for asexual reproduction.
They are
• Spore formation
Ex – ferns and bread mold
• Fragmentation
Ex – spirogyra or pond scum
• Budding
Ex – yeast
• Vegetative reproduction
Ex -Potato, asparagus, onion, ginger, bryophylum
Sexual reproduction: The sexual mode of reproduction in plants involves
the male and female reproductive organs of a flowering plant.
• Ex – china rose, sweet pea, mustard (bisexual
flower)
• Papaya and mulberry (unisexual flower)
Grade. 7 ; Subject: Science Riyad Sabya International School Teacher: Ms. Spandana
2) what are the methods of artificial propagation?
A) Growing plants through artificial methods is known as artificial
propagation. Some methods of artificial propagation are
Cutting: in plants such as rose, sugarcane, and bougainvillea with nodes
and internodes, their stem is cut and planted in the soil to grow into a new
plant.
Grafting: in this method, the two parts of the plant are joined to grow
together. These parts can be of the same or different types of plants.
Layering: in this method, the branch of a plant is bent down to touch the
ground and covered with soil. After some time roots start growing from
the covered part which is then separated from the original plant.
Tissue culture: in this method, some tissue is cut off from the growing
tip of a plant. This tissue is then separated into cells and are put in a
nutrient medium containing inorganic salts, sugars, vitamins, and
hormones. Cells are allowed to grow into small plantlets and then
transferred to pots with soil.
3) Describe the different ways by which seeds are dispersed.
A) The agents for seed dispersal in nature are air, water, animals and even
self-explosion.
Dispersal by wind: seeds of certain plants have features such as wings,
and hair and are lightweight. These seeds are dispersed with the help of
wind.
Ex – grass, cotton, drumsticks
Dispersal by water: the seeds of plants growing in or near water sources
are dispersed with the help of water
Ex – coconut, lotus fruit
Dispersal by animals: the seeds of many fruits are eaten by man, and
other animals pass undigested, and get dispersed when excreted out.
Ex – guava and tomato
Seeds have spines and get stuck to the bodies of animals or the clothes of
humans dispersed to distant places
Ex – xanthium
Grade. 7 ; Subject: Science Riyad Sabya International School Teacher: Ms. Spandana
Self-explosion: fruits of certain plants burst open forcibly after drying.
The seeds of these plants get scattered in all directions.
Ex - legumes, castor, geranium, peas etc
4) Draw a labeled diagram of a flower and explain its parts.
A) The flower is the reproductive organ of a flowering plant. A flower consists
of four whorls.
Sepals: the outermost whorl is of sepals that are green in color.
Petals: the second whorl is of colorful petals.
Stamens: the third whorl has the male sex organs, stamens. The stamen
consists of a filament and an anther. The anther has two lobes, which
contain minute pollen grains. The male gametes are produced inside the
pollen grains.
Pistil: the innermost whorl has the female sex organ, the pistil. It has three
parts ovary, style, and stigma. The ovary is the swollen part in which one
to many ovules are present. The ovule contains an egg or female gamete.
The stigma provides a platform for the pollen grains to germinate.
Grade. 7 ; Subject: Science Riyad Sabya International School Teacher: Ms. Spandana
