Multiple Choice Questions
In a cactus plant, photosynthesis occurs in
- Modified roots
- Modified stem
Reason — In the cactus, leaves are modified into spines. The green leaf like structure is modified into stem, which contains chlorophyll. Thus, the modified stem is the centre of photosynthesis in the cactus plants instead of leaves.
The animal such as birds have
- Light bones with air cavities
- Solid heavy bones
- Heavy pointed bones
- No bones
Light bones with air cavities
Reason — Light bones with air cavities keeps the body of birds light and thus help in flight.
The biotic components of the environment includes
- Green plants
- All of these
All of these
Reason — The living organisms such as plants, animals and decomposers are the biotic components of the environment.
The presence of hollow plant stems is a characteristic of
- Desert plants
- Aquatic plants
- Mountainous tress
- None of these
Reason — The stem of aquatic plant is long, hollow, light and grows well up to the water surface.
Slow breathing is the characteristic of
- Desert Animals
- Aquatic Animals
- Aerial Animals
- Land Animals
Reason — Slow breathing is the characteristic of desert animals because certain amount of moisture is always lost due to evaporation in the respiratory passage during breathing.
Diversity of organisms is found in different habitats because of different adaptations for
- Average temperature
- Soil type
- Annual precipitation
- All of these
All of these
Reason — Organisms adapt to different abiotic factors such as average temperature, soil and annual precipitation in different ways. That is why a diversity of organisms is present in different habitats.
Answer the Questions
List any four abiotic factors which affect different living beings.
Four abiotic factors affecting different living beings are:
Define the following: Habitat, Adaptation.
Habitat — The natural home of an organism and its immediate surroundings is called its habitat. The habitat of any living creature should be a place where it can find shelter, food, water and suitable conditions for breeding.
Adaptation — Adaptation is the development of any structure or function in an organism which makes it more efficient for survival in a particular environment or habitat, i.e. adaptations are the changes in the body or behavior of an organism that enables it to survive comfortably and successfully in a habitat.
Describe any two adaptations seen in desert plants.
The two main adaptations seen in desert plants are
Most cacti desert plants have spines instead of leaves. Leaves would lose water through transpiration.
Photosynthesis is carried out by the thick green stem.
Describe the aerial adaptations in birds.
Various aerial adaptations found in birds are:
- Body shape — The body of birds is streamlined. Necks stretched forward with the head pointed in front and a narrowed tail at the end provide them a sleek shape. The body surface is smooth to minimize resistance against air.
- Wings — The forelimbs are modified into wings. The whole length of the forelimbs carries long light feathers.
- Steering and brakes — The feathers on the tail help to slow down the speed and also help in steering (changing direction).
- Wing muscles — These are the strong, active and enlarged breast muscles which support and help in the movement of wings.
- Cutting down the body weight — Except for the most necessary bulky heavy wing muscles, the rest of the bird's body tends to be light to facilitate flight.
- Bones have air cavities.
- Much less water is required in the body. The birds excrete solid urine (formed of uric acid instead of urea which otherwise requires much water to be excreted out).
Briefly explain the term "Habitat".
The natural home of an organism and its immediate surroundings is called its Habitat. The habitat of any living creature should be a place where it can find shelter, food, water and suitable conditions for breeding. The special feature of habitat is that it includes all the physical characteristics around it (air, water, temperature, etc.) along with the surrounding plants and animals. There are three types of habitat
- Aquatic habitat
- Terrestrial habitat
- Aerial habitat
Give two adaptations in animals found in the mountain habitat.
The two adaptations in animal found in the mountain habitat are:
- The oxygen content in the mountain air is thin. So the blood of the most of these animals contains more red blood cells. This help them to breath in sufficient oxygen even when air pressure is low.
- Some animals hibernate or go for a long winter sleep when the temperatures are very low. In this way, they conserve their energy and survive the winter without food. Frogs and hedgehogs are some animals which hibernate.
How is a whale similar to a fish in adaptation to life in water? Explain any two features.
Two features of whales similar to a fish in adaptation to life in water are:
- Like fish, the huge body of whale is also streamlined in a spindle shape.
- Its front legs are modified into paddles or flippers for kicking water and hind limbs are absent.
List the environmental factors that influence a habitat.
The environmental factors that influence a habitat are:
- Climatic condition
- Plant and Animal
Differentiate between an aquatic habitat and a terrestrial habitat.
Difference between an Aquatic habitat and Terrestrial habitat:
|Aquatic Habitat||Terrestrial Habitat|
|Aquatic habitat includes plants and animals living in rivers, lakes, ponds and seas.||Terrestrial habitat includes plants and animals living on land.|
|Examples — Fish, Water Lily, Lotus, etc.||Examples — Cactus, Camel, Mountain goat, Pine tree, etc.|
Name any three types of terrestrial habitat.
Three types of terrestrial habitats are:
- Desert habitat
- Mountain habitat
- Polar habitat
Name two types of terrestrial habitats with low temperatures.
Two types of terrestrial habitats with low temperatures are:
- Polar habitat
- Mountain habitat
Complete the table given below. Write down two points in each given column.
|Habitat||Environmental factors||Plant Adaptations||Animal adaptations|
|Habitat||Environmental factors||Plant adaptations||Animal adaptations|
|Aquatic habitat||1. Survival in water.|
2. Diffusion of gases for respiration and photosynthesis.
|1. In Vallisneria, the leaves are thin, elongated, ribbon-like to expose more surface to the light entering into water.|
2. In Water Lily, Stomata are present only on the upper surface of the leaves that is exposed to air for diffusion of gases.
|1. Aquatic animals have streamlined body that offers least resistance during its forward movement in water.|
2. Fishes have gills that serve as their breathing organs in water.
|Mountain habitat||1. Rocky land, snow and ice laden regions|
2. Cold climate, low temperature.
|1. Trees like Pine, Fir and Cedar are cone shaped with sloping branches to easily slide off rain water and snow.|
2. The trees have needle like leaves (e.g. Pine tree) to help in water conservation by reducing transpiration as the ground surface is rocky.
|1. These animals have thick skin covered with fur to protect against cold (e.g. Mountain Goat, Yak).|
2. They have strong hooves for running up on rocky slopes of the mountains.
|Desert habitat||1. High daytime temperatures and low night time temperatures.|
2. Scarcity of water.
|1.Desert plants like Cactus are succulent plants, i.e., they store water in their fleshy tissues and depend on this stored water for photosynthesis.|
2. Their leaves are reduced in the form of spines to minimize water loss through transpiration.
|1. The camel can raise its body temperature 4°-5°C higher than outside temperature to reduce water loss through perspiration.|
2. The eyes of the camel are provided with long eyelashes to protect them from the harsh rays of the sun and the sand in the deserts.
Describe how pollination occurs in vallisneria?
Vallisneria is well developed for cross pollination. It is a dioecious plant where male and female plants are separate. Pollination occurs with the help of water and such flowers are called hydrophilous. The male flowers are very small and on maturity, get detached. They float on the surface of water. The female flowers remains float on long stalks. Free floating male flowers pollinate the female flowers on the surface of water.
State the "water saving methods" in a camel.
The water saving methods in a camel are:
- Little and thick urine — When deprived of water, the camel passes out very little urine and it is quite thick.
- Semi-dry faeces — The dung passed out is quite dry.
- Perspires very little — The camel can tolerate high outside temperature up to 40°C to 45°C as its own body temperature can go up to 41°-42°C and therefore the need to perspire is reduced.
- Slow breathing — Certain amount of moisture is always lost due to evaporation in the respiratory passages during breathing. Slower the rate of breathing, lesser the loss of water as water vapour in the air breathed out.
- Water "storage" in muscles — The camel's muscles can withstand the shortage of water and can shrink considerably. Once the water is available, the camel can drink sufficient water and the muscles swell up.
- Water from the "fat" of the hump — While starving, the fat is oxidized to yield energy as well as water.