Class 7 | Science | Chapter- 12 | Reproduction in Plants Notes

Class 7           Science

Chapter- 12

Reproduction in Plants Notes

Reproduction- The production of new individuals from their parents is known as reproduction.

All organisms multiply or reproduce their own kind.

MODES OF REPRODUCTION

Most plants have roots, stems and leaves. These are called the vegetative parts of a plants.

The flowers perform the function

of reproduction in plants. Flowers are
the reproductive parts of reproductive parts a plant. A flower may have either the male part or the female part or both male and female parts.

In plants there are two modes of reproduction, asexual and sexual.
Asexual reproduction-  In asexual reproduction reproduction plants can give rise to new plants without seeds.

There are several methods of asexual reproduction such as fragmentation, budding, spore formation and vegetative propagation.

Sexual reproduction- In sexual reproduction new reproduction plants are obtained from seeds.
Sexual reproduction involves the fusion of male and female gametes.

Vegetative propagation- In vegetative propagation new plants are produced from different vegetative parts such as leaves, stems and roots.

Cutting-  Cut a branch of rose or champa with a node. This piece of branch is termed a cutting.

Buds- Apart from flower buds, there are buds in the axil (point of attachment of the leaf at the node) of leaves which develop into shoots. These buds are called vegetative buds.

Eyes- Observe the scars on Fresh Potato.
You may find bud(s) in them. These scars
are also called “eyes”.

Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. The small bulb like projection coming out from the yeast cell is called a bud. The new organism remains attached as it grows, separating from the parent organism only when it is mature, leaving behind scar tissue. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical to the parent organism.

Fragmentation -the process or state of breaking or being broken into fragments.

Spore Formation- Spore formation is a method of asexual reproduction which is found in non flowering plants such as fungi (Rhizopus) and bacteria. In this method of reproduction, the parent plant produces hundreds of tiny spores which can grow into new plants.

SEXUAL REPRODUCTION
The stamens are the male reproductive part stamens and the pistil is the female reproductive pistil part.

The flowers which contain either only the pistil or only the stamens are called unisexual flowers. The flowers which contain both stamens and pistil are called bisexual flowers.

A pistil consists male gametes of stigma, style and ovary. The ovary contains one or more ovules.
The female gamete female gamete or the female gamete egg is formed in egg an ovule.
In sexual reproduction a male and a female gamete fuse to form a zygote.

Pollination
The transfer of pollen from the anther to the stigma of a flower is called pollination.

If pollination the pollen lands
on the stigma of the same flower it is
called self-pollination.
 When 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, it is called cross-pollination.

Fertilisation-
The zygote process of fusion of male and female gametes (to form a zygote) is called
fertilisation.

The cell which results after fusion of fusion
the gametes is called a zygote.
The zygote develops into an embryo.

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.

SEED DISPERSAL

Seed dispersal is aided by wind, water and animals.

 Seed dispersal helps the plants to

 (i) prevent overcrowding,

 (ii) avoid competition for sunlight, water and minerals and 

(iii) invade new habitats

Class 7 | Science | Chapter- 11 | Transportation in Animals and Plants Notes

Class 7           Science

Chapter- 11

Transportation in Animals  and Plants Notes

CIRCULATORY SYSTEM-

Circulatory system consists of the heart and blood vessels.

Blood-

Blood is the fluid which flows in blood vessels. It transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.

The fluid part of the blood is called plasma. One type of cells are the red blood cells(RBC) which contain a red pigment called haemoglobin.

The blood also has white blood cells(WBC) which fight against germs that may enter our body.

After cut on the body blood is flow and the clot is formed because of the presence of another type of cells in the blood, called platelets.

Blood vessels-
Two types of blood vessels are present in the arteries and veins of the body.

Arteries- Arteries oxygen-rich blood from the heart to all parts of the body. Since the blood flow is rapid and at a high pressure, the arteries have thick elastic walls.

Veins- Veins the vessels which carry carbon dioxide-rich blood from all parts of the body back to the heart. The vein have thin walls. There are valves present in veins which allow blood to flow only towards the heart.

The arteries divide into smaller vessels. On

reaching the tissues, they divide further

into extremely thin tubes called capillaries. The capillaries join up to form veins which empty into the heart.


Heart-
The heart is an organ which beats continuously to act as a pump for the transport of blood, which carries other substances with it.

The heart is located in the chest cavity with its lower tip slightly tilted towards the left.
the heart has four chambers. The two upper chambers are called the atria (singular:atrium) and the two lower chambers are called the ventricles.
The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.

Heartbeat-
The walls of the chambers of the heart
are made up of muscles. These muscles
contract and relax rhythmically. This
rhythmic contraction followed by its relaxation constitute a heartbeat.

• The human heart beats about 70–80 times per minute in an adult person. This is called heart rate.

EXCRETION IN ANIMALS-

• Removal of waste products from the body is called excretion.
• Excretory system of humans consists of two kidneys, two ureters, a urinary bladder, and urethra.
• Salts and urea are removed along with water as sweat.
• Fish excrete waste substances which directly dissolve in water.
• Birds, insects and lizard excrete uric acid in semi-solid form.

Excretory system in humans-

• The waste which is present in the blood has to be removed from the body.
• When the blood reaches the two kidneys it contains both useful and harmful substances. The useful substances are absorbed back into the blood. The wastes dissolved in water are removed as urine. 
• From the kidneys, the urine urine goes into the urinary bladder through tube-like ureters. It is ureters stored in the bladder and is passed out through the urinary opening at the end of a muscular tube called urethra.

TRANSPORT OF SUBSTANCES IN PLANTS-

• Water and mineral nutrients are absorbed by roots from the soil.
• Nutrients are transported along with water to the entire plant via the vascular tissue called xylem.
• The vascular tissue for the transport of food to the various parts of the plant is phloem.
• A lot of water is lost by plants in the form of vapour through stomata during transpiration.
• Transpiration generates a force which pulls up water absorbed by the
• roots from the soil, to reach the stem and leaves.