Science 5 Marks Questions

Column I	Column II
Bud	Yeast
Eyes	Potato
Fragmentation	Spirogyra
Wings	Maple
Spores	Bread mould

Seed dispersal occurs by the following agencies.

Dispersal by animals − There are many ways by which birds and animals can disperse seeds. For example, birds and animals can eat the fruits and excrete the seeds away from the parent plant. Some seeds have barbs or other structures that get attached to the animal’s body and are carried to new sites. Some fruits have hooks on them which cling to fur or clothes.

Dispersal by wind − Seeds that get dispersed by wind are usually smaller in size or they have wings or hair-like structures. For example, winged seeds of drumsticks, hairy fruit of sunflower, etc. are dispersed by wind.

Dispersal by water − Many aquatic plants or plants that live near water has seeds that can float and are carried away by water. For example, coconuts can float and are dispersed by water.

Dispersal by explosion − Sometimes the seeds are dispersed by the bursting of fruits with sudden jerks. The seeds get scattered or distributed far from the parent plant. Examples of such plants are castor and balsam.

When pollen lands on stigma, it germinates and gives rise to a pollen tube that passes through the style and reaches the ovary of a pistil. When the pollen tube reaches an ovule, it releases the male gametes. A male gamete fuses with a female gamete in the ovule. This process is known as fertilisation. The cell which is formed after the fusion of a male and a female gamete is known as zygote. This zygote divides several times in order to form the embryo present inside the seed.

Process of fertilisation

When the reproduction in an organism includes two types of gametes, i.e male and female from two different parents, it is called sexual reproduction. The sexual reproduction takes place by the fusion of male and female gametes by the process called fertilisation to form zygote.

Sexual reproduction [fertilisation) in plants The different steps that take place during sexual reproduction in plants are,

• The pollens are deposited on stigma and begins to germinate.
• Pollen tube containing male gametes reaches to the ovary of flower.
• The tip of the pollen tubes gets dissolved and male gametes comes out of the pollen tube.
• Inside the ovary male gametes fuse with the female gamete or egg present in the ovule.
• The fusion of both the gametes will result into a fertilised egg cell which is also called as zygote.

The mode of dispersal of the seeds with their characteristic properties are as follows:

1. Seeds with wings: g. Seeds of drumstick and maple are light weighted and can be blown away by air. Thus, these are dispersed by wind.
2. Small and light seeds: g. Seeds of grasses and cotton (having hairy growth) are also dispersed through wind.
3. Seeds with spines/ hooks: e.g. Seeds of Xanthium, Urena, the hooks or spines of seeds attach to the animal body. When animals move to other places and rub their body with tree, etc. These seeds fall from their body and get dispersed. Therefore, these are dispersed through animals.

The various modes of asexual reproduction in plants are as follows:

1. Vegetative propagation: It is the ability of a plant to produce new plants from roots, stems, leaves, and buds. Vegetative propagation is divided into two types.

• Natural vegetative propagation: This type of vegetative propagation occurs easily in nature and involves simple vegetative parts. Potato plant sprouting from an eye is a common example.
• Artificial vegetative propagation: This type of vegetative propagation is performed manually and generally occurs in laboratory conditions. The formation of a complete plant from a stem cutting of rose is a common example of this method.

2. Budding: It involves the formation of a new individual from a bulb - like projection called a bud. The bud grows and gets detached from the parent to form a new individual. It is commonly observed in yeast.

3. Fragmentation: It is a form of asexual reproduction where a new organism is formed from the fragments of the parent body. It is the only mode of asexual reproduction in Spirogyra.

4. Spore formation: Many non-flowering plants reproduce through spore formation. Spores are tiny cells protected by a thick wall. Fungi such as bread moulds reproduce asexually using this method.

Seed dispersal occurs by the following agencies.

1. Dispersal by animals - There are many ways by which birds and animals can disperse seeds. For example, birds and animals can eat the fruits and excrete the seeds away from the parent plant. Some seeds have barbs or other structures that get attached to the animal’s body and are carried to new sites. Some fruits have hooks on them which cling to fur or clothes.
2. Dispersal by wind - Seeds that get dispersed by wind are usually smaller in size or they have wings or hair-like structures. For example, winged seeds of drumsticks, hairy fruit of sunflower, etc. are dispersed by wind.
3. Dispersal by water - Many aquatic plants or plants that live near water has seeds that can float and are carried away by water. For example, coconuts can float and are dispersed by water.
4. Dispersal by explosion - Sometimes the seeds are dispersed by the bursting of fruits with sudden jerks. The seeds get scattered or distributed far from the parent plant. Examples of such plants are castor and balsam.

Basis of differentiation	Self pollination	Cross pollination
Meaning	The process of transfer of pollen grains from anthers to the stigma of a flower, but when this process is between the flowers of the same plant than the term is called self-pollination.	The process of transfer of pollen grains between the flowers of the different plants of the same species is called cross-pollination.
It involves	Single plant.	Two different plants of the same species.
Self pollination	Self-pollination occurs in perfect flowers only.	It occurs in both imperfect and perfect flowers.
Pollinating agents	Pollinating agents are not required.	Pollinating agent such as wind, water, insects, etc. is not required.
Pollen grains	Less number of pollen grains are produced.	A large number of pollen grains are produced.
Examples	Wheat, rice, pea, orchids, barley, tomatoes, peaches, apricot.	Mulberry, maize, pumpkins, strawberries, blackberries, plums, grapes, daffodils, maple, catkins, grasses.

Self pollination: Refers to the transfer of pollen from the anther (male reproductive part) of a particular flower to the stigma (female reproductive part) of the same flower.
Cross pollination: Refers to the transfer of pollen from the anther (male reproductive part) of one flower to the stigma (female reproductive part) of the another flower of a different plant (of same or different species), with the help of an external agent.

The method of seed dispersal in the fruits and the parts which help in the seed dispersal:
Name of fruits bearing plants Agents through which seeds are dispersd Parts or seeds which helps in dispersal,

Name of fruits bearing plants	Agents through which seeds are dispersd	Parts or seeds which helps in dispersal
Drumstick	Air/wind	Winged seeds
Sunflower	Wind	Hairy seeds
Gokhru	Animal	Spines and Hooks
Coconut	Water	Fibrous coating
Lotus	Water	Thalamus float in water
Poppy	Explosion	Pericarp bursts
Grass	Wind	minute, light weighted seeds

The process in which the male gamete fuses with female gamete to form a new cell (called zygote) is called fertilisation.
When the pollens are deposited on the stigma of the pistil, it begins to germinate. After sometime, a long pollen tube is developed from the pollen grain which passes through the style towards the female gametes in the ovary. The male gametes move down the pollen tube and the tube enters the ovule present inside the ovary.
The tip of pollen tube bursts and the male gamete comes out of the pollen tube. Inside the ovary, the male gametes fuse with the female gametes present in the ovule to form a fertilised egg cell which is called zygote.
The zygote develops into an embryo which is a part of a seed that develops into a new plant.

When pollen lands on stigma, it germinates and gives rise to a pollen tube that passes through the style and reaches the ovary of a pistil. When the pollen tube reaches an ovule, it releases the male gametes. A male gamete fuses with a female gamete in the ovule. This process is known as fertilisation. The cell which is formed after the fusion of a male and a female gamete is known as zygote. This zygote divides several times in order to form the embryo present inside the seed.

1. When the bread piece is kept in a moist and warm place for few days, bread mould grows on the bread piece.
2. The thread-like projections are called hyphae or mycelium.
3. The thin stem having knob-like structure on the top is called sporangia or sporangium which contains hundred of minute spores.
4. Bread mould shows asexual mode of reproduction.
5. These spores are present in the air and when favourable conditions arrive, the grow into new plants.

Advantages of vegetative reproduction:

• Some of the plants such as bananas do not reproduce from seeds at all. They multiply only vegetatively.
• Vegetative reproduction is faster.
• Sometimes the seeds produced are not viable or fit that means they cannot form new plants.
• It is the embryo of the seeds that forms the new plants. If the embryo is not there or is destroyed, the new plants cannot be formed.
• The new plants formed through vegetative reproduction are exactly like the parent plants. Disadvantage of vegetative reproduction
• Since vegetative reproduction produces an exact copy of the parent, some undesired qualities of the parent plant also pass on to the plants of new generation.

Differences between sexual and asexual reproduction:

Asexual reproduction	Asexual reproduction
It requires only one parent.	It requires two parents.
In asexual reproduction, newly developed plants are identical to theparent and to each other.	In sexual reproduction, newly developed plants are not identical to parents.
Special reproductive parts are not required for asexual reproduction.	Flower is the reproductive part of a plant which contains the sexual organs of a plant. These are important for sexual reproduction.
Examples are yeast, rose, jasmine, potato, etc.	Examples are flowering plants, such as Hibiscus, corn, papaya, etc.

The main parts of a flower are,

1. Sepals These are the green leaf-like outermost circle of the flower. All the sepals are together referred to as calyx. The function of calyx is to protect the flower when it is in bud form.

Petals These are the colourful and most attractive part of flower. These lie inside the sepals. All the petals are together referred to as corolla. These are scented and attract insects for pollination.

2. Stamen It is a male reproductive organ of plant. These are the little stalks with swollen top and lies inside the ring of petals. The stamen is made up of two parts, i.e. filament and anther. The stalk of stamen is called filament and the swollen top of stamen is called anther.

Anther contains the pollen grain which have male gamete in it. Pollen grains are exposed when the anther ripens and splits. These appear as the yellow powder like substance which is sticky in nature. Flowers usually have a number of stamens in it.

3. Pistil It is the female reproductive part of a flower that lies in the centre of a flower. These are flask-shaped structure which is made up of three parts, i.e. stigma, style and ovary.

The top part of pistil is called stigma. It receives the pollen grains from the anther during pollination. The middle part of the pistil is tube-like structure called style which connects stigma to the ovary.

4. The swollen bottom part at the base of pistil is called ovary.

The ovary makes ovules and stores them. These ovules contain the female sex cells also called as egg cell. It is the female gamete of flower. Pistil is also called as carpel.
The pistil is surrounded by several stamens. The base of the flower on which all the parts of flower are attached is called receptacle.

In sexual reproduction, new plants are obtained from seeds. The flowers are the reproductive parts of a plant. The stamens are the male reproductive part and the pistil is the female reproductive part. A pistil consists of stigma, style and ovary. The ovary contains one or more ovules. The transfer of pollen from the anther to the stigma of a flower is called pollination. 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. The process of fusion of male and female gametes (to form a zygote) is called fertilization. The zygote develops into an embryo. After fertilization, 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. Seeds and fruits of plants are carried away by wind, water and animals and reproduced again on the grounds.

The various parts of a flower whose functions are mentioned above are labelled as follows:

Fungus reproduces by means of spores. Spores are covered by a protective hard coat. Spores can survive in extreme conditions like high temperature and low humidity because of the protective hard coat.

Modes of reproduction that evolve only one parent is called unisexual reproduction.

1. Fission: The mode of reproduction in which unicellular organism split into two equal halves and produce new ones is called binary fission. For example amoeba and bacteria
2. Fragmentation: The mode of reproduction in which body of plant breaks up into smaller fragments and each fragment grows into a new individual is known as Fragmentation e.g. Spirogyra, algae.
3. Budding: The mode of reproduction in which small buds develop and get separated and matured into new organisms is called Budding. e.g. Yeast, Hydra, Bryophyllum.
4. Spore formation: The mode of reproduction takes place by means of spores is called spore formation. e.g. algae and fungi.

The spores are covered by thick walls that protect them until they come into contact with another moist surface and can begin to grow.

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. The plants like rose or champa can be propagated through Vegetative propagation.

• Vegetative Propagation by Roots: e.g. Dalbergia sissoo.
• Vegetative Propagation by Stem: e.g. Banana.
• Vegetative Propagation by Leaf: e.g. Bryophyllum.

Artificial methods:

• Cutting: e.g. Sugarcane.
• Grafting: e.g. Desi Mango.
• Budding: e.g. Rose.
• Layering: e.g. Jasmine.

1. Vegetative propagation is the process of reproduction in which new plants are produced from different parts of old plants like stem, roots or leaves.
2. Cutting and grafting method are two methods where stem is used for vegetative propagation.
3. Mango and rose are two plants cultivated using vegetative propagation.

This is an asexual method of reproduction.

4. Ria is curious, inquiring who wants to gain knowledge about process occurring around here.

Following are the parts of flowers:

1. Sepal: Green leafy part of flower that protect flower in bud condition.
2. Petal: Coloured leafy part of flower that attract insect for pollination.
3. Stamen: The male parts of flower that contain pollen grain.
4. Pistil: The female parts of flower that contain ovary at bottom.

1. A flower is the reproductive part of plant which helps in sexual reproduction. A flower ensures the occurrence of process of fertilisation.
2. Yes, flower aids in both pollination and fertilisation. Different colours and fragrance of flowers attract insects to them causing dispersal of pollen grain ensuring pollination. Fertilisation occurs in the ovary of the flower after pollination of male and female parts.
3. Number of some flowers can either have male or female parts on them, these flowers are called unisexual. Some flowers have both, the male and female parts on them so they are called bisexual flowers.
4. Ravi is aware, sincere, helpful as he helps others and knowledgeable while his sister is inquisitive, ready to acquire new knowledge and observant.

1. The given figure is of ginger tuber.
2. Asexual reproduction is seen in this plant.
3. Ginger is a stem.
4. Various parts of this plant can be shown as follows:

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