BIO reproduction in plants

Reproduction

Reproduction means producing young ones of the same kind

Modes of reproduction in plants

Modes of reproduction in plants are of two kinds

• Asexual reproduction

• Sexual reproduction

Asexual reproduction

Reproduction where only one parent is involved and there is no formation or fusion of male and female gamets

Sexual reproduction

Reproduction in plants where both parents are involved and there is formation or fusion of male and female gamets.

Which organisms reproduce by asexual reproduction

Lower organisms like

• Fungi

• Bacteria

• Algae

Vegitative reproduction

In some higher plants, the vegitative parts of the plant like root stem or leaves also help in producing new plants

Types of asexual reproduction

Types are

• Binary fission

• Budding

• Fragmentation

• Spore formation

• Vegitative propagation

Vegetative propagation

in some higher plants vegetative parts like roots, stems and leaves also help in producing new plants

binary fission

Some organisms like bacteria reproduce by binary fission. In this method the nucleus splits into two and then the entire cell splits across the middleto form two identical daughter cells. In organisms like chlorella and chlamydomonas one cell divides into four daughter cells this is called multiple fission.

Budding

This method is commonly seen in yeast. In this the parent cell produces an outgrowth called a bud. this bud grows, and detaches along with its daughter nuclei from the parent body and grows into a independent cell

Fragmentation

In organisms like spirogyra that is made up of ribbon like filaments, one filament grows and breaks of into two or more parts called fragments. These fragments grow into independant cells

Spore formation

Spore formation is commonly seen in fungi and plants like mosses and ferns that that bear spores on the under side of their leaves

Propagules

The vegetative parts of the plant that are capable of producing new plants are called propagules

Natural vegetative propagation can be carried by what parts

-Roots

-Stems

-Leaves

REPRODUCTION BY STEM

The stems of plants like common grass and mint grow horizontally parallel to the ground. New roots and shoots grow from these nodes. The roots grow downwards while the shoots grow upwards to form a new plant.

Name some modified stems

• GINGER

• POTATO

• ONION

Why are ginger, potato and onion called modified stems

Ginger, potato, and onions are called modified stems as they perform additional functions like food storage and vegetative propagation

What grows out of ginger to produce new plants

Axillary buds grow out from the nodes of ginger to produce new plants

REPRODUCTION BY LEAVES

Leaves of some plants like bryophyllum produce buds in the notches of their margins. When these leaves fall into moist soil they grow into new plants

REPRODUCTION BY ROOT

Plants like sweet and asparagus develop numerous large swollen fleshy roots

why is a carrot considered a biennial plant

It is called a biennial plant as its roots grow vegetatively in the first year, and the next year the produces flowers and seeds which die by the end of the next year. Buds produced at the base of the old stem just above the tap root are meant for vegetative propagation.

ADVANTAGES OF VEGETATIVE PROPAGATION

• Reproduction by vegetative parts takes place in a shorter time

• New plants thus produced spread very fast in a small area

• It is a surer method of propagation

• All good characters of the mother plant are retained by the daughter plant

DISADVANTAGES OF VEGETATIVE PROPAGATION

• As all plants developed by vegetative propagation are genetically identical, they are all likely to be affected simultaneously if a disease spreads in the farm

• Dispersal of plants does not take place on its own. Daughter plants, so developed tend to remain nearby and are restricted to a particular area. Thus leading to competition of resources

ARTIFICIAL VEGETATIVE PROPAGATION

• CUTTING

• LAYERING

• GRAFTING

• MICROPROPAGATION

Micropropagation

It is the propagation of plants by tissue culture technique.If vegetative propagation is not possible in a plant then the tissue of vegetative buds or shoot apex or any other suitable part of the plant can be used as an explant for micro propagation. The explant is treated with sterilisation chemicals to prevent microbial growth. Cells grow and divide to form a mass called callus. Some growth regulators are added. The callus differentiates into plant parts looking like a tiny plant called plantlet.

BENEFIT OF PLANT TISSUE CULTURE TECHNIQUE

• It provides rapid propagation of identical individuals. This technique is very productive for superior varieties.

• It is very useful in many cases. The embryo in these seeds can be cultured and micro propagated

LIMITATIONS OF TISSUE CULTURE

• It requires lot of scientific expertise

• It cannot be applied to all cases

• It is not easily applicable in remote agricultural areas

What is the reproductive part of a plant

FLOWER

What’s a stalk

The flower is attached to the shoot by means of a stalk or pedicle.

WHAT ARE THE FORE WHORLS OF A FLOWER

• CALYX

• COROLLA

• ANDROECIUM

• GYNOECIUM

CALYX

It is the outer most part of the flower forming a whorl of green leaf like structures called sepals. During bud stage they protect the flower

COROLLA

Made up of petals that form the second inner whorl arranged after the sepals. These petals are coloured to attract insects for pollination

ANDROECIUM

[The male part ] It is the third whorl after the petals. They consist of delicate thread like structures called stamen. Each stamen is formed of a long narrow thin filament and a broad sac-like bilobed structure called anther at its tip. Each anther contains four pollen sacs that develop pollen grains. The pollen grains contain the male gamets.

What are the male reproductive parts of a flower

STEMENS

GYNOECIUM

[The female part] It consists of carpels the fourth inter most part of the flower also called pistil. Each carpel is formed of three parts :

• OVERY- THE SWOLLEN BASE

• STYLE-THE NARROW THREAD LIKE

• STIGMA- TERMINALLY EXPANDED

WHAT ARE THE FEMALE REPRODUCTIVE PARTS OF A FLOWER

CARPEL

what are ovules

Ovules are the tiny rounded bodies present inside the overy. Each ovule contains an egg cell which later develops into seeds after successful fertilisation

what are the two types of flowers

• BISEXUAL FLOWERS

• UNISEXUAL FLOWERS

BISEXUAL FLOWERS

Flowers containing both male and female parts

UNISEXUAL FLOWER

Flowers containing either only female or male parts

Functions of a flower

It is the reproductive organ of the plant

POLLINATION

The process in which the pollen grains anther are transferred to the stigma of the flower of the same species

two types of pollination

• SELF PLOLLINATION

• CROSS POLLINATION

Self pollination

POLLINATION WITHIN THE SAME FLOWER OR TWO FLOWERS OF THE SAME PLANT

Cross pollination

POLLINATION BETWEEN TWO FLOWERS OF DIFFERENT PLANTS

Agents of cross pollination

• Insects

• Wind

• Water

INSECT POLLINATION

When insects help in pollination such transfer of pollen grains is called insect pollination

CHARACTERISTICS OF INSECT POLLINATED FLOWERS

• These flowers ae large with coloured petals to attract insects

• They contain nectar as food for insects

• These produce sticky pollen grains so that they may stick to the body of insects

WIND POLLINATION

When wind is an agent of cross pollination,it is called wind pollination

CHARACTERISTICS OF WIND POLLINATED FLOWERS

• They are usually small and of dull colours

• They generally have long anthers protruding out of the flower

so that pollen grains may get blown away easily

WATER POLLINATION

Pollination where water acts as an agent of cross pollination is called water pollination. EX VALISSNARIA

CHARACTERISTICS OF WATER POLLINATED FLOWERS

• Flowers are small and light so they can easily float on water

• Male and female plants are borne on different plants

• Pollen grains are produced in large numbers

fun facts

LOTUS AND TRAPA ARE AQUAIC PLANTS BUT THEIR FLOWERS ARE EXPOSED TO AIR AND SO ARE POLLINATED BY INSECTS

FERTILISATION

Fusion of male and female sex cells to produce a zygote

STEPS OF FERTILIZATION READ FROM TB

READ FLOW CHART

POLLEN TUBE

THE TUBE GROWN IN THE STYLE OF A FLOWER DURING FERTILIZATION

ARTIFICIAL POLLINATION

Means the transfer of pollen grains to the stigma manually