Plants & Animals
Class-IV
Chapter- 2
Q.A. Fill in the blanks.
a) Most of animals have the ___________ to move freely by using limbs, wings or fins.b) ____________ is such kind of saline soil environment in Bangladesh.c) Birds and squirrels make their nests in trees or live in tree ____.d) Frogs, turtles and ____________ can live both on land and in water.e) A ____________ is an extremely dry place with very little water and rain.f) ____________ is a large reservoir of saline water.g) A ___________ is a place with many trees and bushes grown densely in natural processes such as Sundarbon, and Sal forest.h) The part of an environment where a plant or an animal lives is called___________.i) A camel stores ________ in its hump.j) Different plants and animals live in different ________ .
3. Short Q/A
2) What causes the environment to change?
Ans: Environmental changes can be caused by natural disasters and human activities.
3) Give at least four habitats of plants and animals.
Ans: There are various types of habitats on Earth such as –DesertForestWetlandOcean
4. Descriptive Questions:
1) How does cactus and camel survive in the desert?
Ans: A desert is an extremely dry place with very little water and rain. The stem and leaves of cactus are succulent and its smooth outermost surface helps to retain water. A camel stores fat in its hump. This stored fat helps it to survive longer period without water or food in desert environment.
2) Why do some plants and animals become extinct?
Ans: Some plants and animals become extinct for the following reason-
a. Destruction of habitats
b. Changed the environment drastically
c. Natural causes such as flood, storm, drought etc.
3) In which region Penguin lives in? What are the characteristics of that region?
Ans: Penguin lives in polar region.
The characteristics of that region are –
a) Extremely cold
b) Ice covered place of earth
Dispersal:
Q.2. Define dispersal. Describe the different ways of seed dispersal.
Ans: The process by which seeds are scattered away from the mother plant is called dispersal.
Some ways of seed dispersal are given below.
1. Dispersal by wind:
Seeds of certain plants are very light and have wing-like structures or hair on them. These seeds are easily carried away by the wind from one place to another. Exaaaaaaaaamples re maple and dandelion seeds.
2. Dispersal by water:
Seeds of plants such as the lotus and coconut are spongy or have a fibrous covering, which helps them to float on water. Water carries these seeds from one place to another.
3. Dispersal by animals:
Some seeds such as cocklebur have spines or hooks. These seeds stick to the bodies of animals and birds, and are thus carried away from the mother plant.
Birds and animals eat fruits of various plants. Undigested seeds of these fruits pass through their digestive systems intact and are dispersed to other areas.
4. Dispersal by explosion:
The fruits of some plants such as peas, and beans burst open when they are ripe, scattering the seeds in all directions. This method of seed dispersal is called explosion.
Germination:
Q.1. Describe the process of germination.
The process by which a seed produces a new plant is called germination.
Not all seeds germinate into new plants. Some seeds are eaten up by birds and insects; some get destroyed by the rain or the wind; while some seeds do not get the right conditions to germinate.
All seeds need air, water, and warmth to germinate into seedlings. If a seed does not receive any one of the three, it will not germinate. The following picture shows the different stages of germination in a bean seed.
During the early stages of germination, the seedling gets the food required for its growth from the cotyledons. After the food stored in the cotyledons has been used up, it gets its food from the soil. The seedling absorbs water and nutrients from the soil with the help of its roots. Air (which is required for germination) also reaches the seed through pores in the soil. It develops leave and grows into a plant. That is why soil is so important for plant growth.
Stages of germination in a bean seed:
1. the seed gets air, water, and warmth.
2. The seed soaks up water; seed coat breaks and the root emerges.
3. The new plant develops roots and a shoot.
4. As the plant grows in size, it develops leaves.
5. The cotyledons shrink and disappear.
Q/A:
1. What is a seed coat?
Ans: The outer covering of a seed, which protects the baby plant inside it, is called the seed coat.
2. Name the three things that the seed requires to germinate.
Ans: All seeds need air, water, and warmth to germinate into seedlings. If a seed does not receive any of the three, it will not germinate.
3. What are cotyledons?
Ans: Part of the seed that store food for the baby plant are called cotyledons.
4. Why do plants scatter their seeds?
Ans: After they germinate, they will compete for air, water, light, nutrients, and space to grow. As a result, many of them would die. In order to ensure that they do not grow too close to one another, in nature, many plants scatter their seeds.
5. Name any three parts of the plant other than the seed from which a new plant can grow.
Ans: A new plant can be grown from the top portion of a carrot. A potato has buds called 'eyes' on its surface. Any piece of potato with an eye can grow into a new plant. Ginger will grow a leafy shoot when planted in soil. Rose, hibiscus, and money plant, new plants can grow from just stem cuttings of the mother plant.
6. What is step farming?
Ans: In hilly regions, people grow corps by cutting steps into the mountainside. This is known as step farming or terrace farming.
7. What are crops?
Ans: Plants that are grown in large quantities in a particular area or region during a particular season are called crops.
8. Write differences between rabi and kharif crops with examples.
Ans: Crops grown from Junbe to October are known as kharif crops. These crops depend largely on the monsoon rains. Examples of such crops are rice and maize.
Crops grown from November to April are called rabi crops. These crops do not depend on the monsoon rains. Examples of such crops are wheat and legumes.
9. What is agriculture?
Ans: The practice of growing plants on a large scale for food or other purposes is called agriculture.
10. Write down the stages of agriculture?
The various stages of agriculture are as follows.
1. The field is ploughed.
2. Manure or fertilizers are added to the soil.
3. Seeds are sown.
4. The crops are irrigated (watered).
5. The crops are sprayed with chemicals called pesticides to protect them from pests.
6. The crops are harvested.
Chapter-6:
Animals: Habitat & Adaptation
Q. 1. What is habitat?
Ans: The area where a particular animal naturally lives is called its habitat.
Q. 2. What is adaptation?
Ans: Changes in the feature or behaviour of an organism that help it to survive in its habitat is called adaptation.
Q.3. What does a habitat provide an animal with?
Ans: An animal's habitat provides it with air, water, food, and shelter. The home of an animal is found within its habitat. For example, a lion's home is the den and the forest is its habitat.
Q.4. Name the different types of habitats.
Ans: There are different types of habitats on Earth:
forests
deserts
polar regions
mountains
oceans
freshwater
Q.5. Name any four types of body coverings in animals.
Ans: An animal's body covering helps it to live in a particular habitat. The name of body coverings in animals are -
crocodile
shell
fish
bear
Q.6. Describe the polar regions and mountains animals.
Ans: The Earth's polar regions (Anterctica and Arctic) and high mountains are extremely cold and covered with snow. Polar bears, seals, and walrus are found in polar regions, whereas yaks and mountain goats are found on mountains.
Q.7. Name any two breathing organs in animals.
Ans: The nose and lungs are two breathing organs in animals.
Q.8. Name any four organs for movement in animals.
Ans: legs, limbs, wings, arms are the name of four organs for movement in animals.
Q.9. Describe the different types of habitat listing special features of each.
Ans: The different types of habitat are -
a) Forest:
A forest is a large area that is covered with trees and plants. Forests provide shelter to a large variety of animals.
b) Desert:
A desert is a dry, often sandy region that receives very little rainfall. It is usually very hot during the day and cold during the night.
c) Polar Regions and Mountains:
The Earth's polar regions (Anterctica and Arctic) and high mountains are extremely cold and covered with snow. Polar bears, seals, and walrus are found in polar regions, whereas yaks and mountain goats are found on mountains.
d) Ocean:
The ocean is a large, continuous body of saltwater that covers two-thirds of the Earth's surface.
It is the world's largest habitat.
e) Freshwater:
Rivers, lakes, and ponds, are examples of freshwater habitats.
10. Describe the different body coverings of animals with examples.
Ans: The different body coverings of animals are
Fishes are covered with a layer of flexible, overlapping scales.
Crocodile has thick, plate-like scales.
tortoise and snail have a shell to protect their soft and delicate bodies.
Bodies of birds are covered with feathers, which help to keep them warm.
The body of a bear is covered with fur, to keep it warm.
Beetles have a hard outer covering called cuticle that protects the soft body.