CLASS VII

Chapter 1 : Nutrition in Plants

Fill in the blanks:

1. The components of food which are necessary for our body are called _______________

2. Green plants synthesise their own food themselves by the process of __________________.

3. ______________________ is the mode of taking food by an organism and its utilization by the body.

4. Complex chemical substances such as ______________ are the products of photosynthesis.

5. ___________________ gas is produced during photosynthesis.

6. Organisms that are dependent on others for their nutrition are called ______________________

7. _________________ are the tiny pores present on the surface of the leaves and are surrounded by guard cells.

8. ____________________is the ultimate source of energy for all living organisms.

9. Organisms which derive their nutrition from dead decaying matter are called _______________.

10. Some organisms live together and share shelter and nutrients, this is called _____________________.

11. Carbohydrates are made up of _________,__________ and __________.

Name the following :

1. A bacterium that can take atmospheric nitrogen and convert it into a soluble form.

2. An insectivorous plant.

3. The mode of nutrition in mushrooms.

4. The indicator used to test the presence of starch in leaves.

 HEAT AND TEMPERATURE
Questions: Fill in the blanks :

(a) The hotness of an object is determined by itS______________.

(b) Temperature of boiling water cannot be measured by a __________ thermometer.

(c) Temperature is measured in degree________.

(d) No medium is required for transfer of heat by the process of ________.

(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of ___________.

(f ) Clothes of _______ colours absorb heat better than clothes of light colours.

Questions: Match the following :

(i) Land breeze blows during  
(ii) Sea breeze blows during-
(iii) Dark coloured clothes are preferred during 
(iv) Light coloured clothes are preferred during-

Questions: What is heat?

Heat is a form of energy, entry or exit of which correspondingly increases or decreases internal energy of a body when no work is done on the body or by the body.

Questions: What is temperature?

A reliable measure of the hotness of an object is its temperature. Temperature is measured by a device called  thermometer.

Questions:What is clinical thermometer?

The thermometer that measures our body temperature is called a clinical thermometer

A clinical thermometer consists of a long, narrow, uniform glass tube. It has a bulb at one end. This bulb contains mercury.

Questions: Why clinical thermometer ranging 35^oC to 42^oC.?

The normal temperature of human body is 37°C.The temperature of human  body normally does not go below 35^oC or above 42^oC. That is the reason that this a clinical thermometer has the range 35^oC to 42^oC.

Questions: What is the use of the m a x i m u m - m i n i m u m thermometer?

Different types of thermometers are used for different purposes. The maximum and minimum

temperatures of the previous day, reported in weather reports, are measured by a  thermometer called the m a x i m u m - m i n i m u m thermometer.

Questions: What is the range of a laboratory thermometer?

The range of a laboratory thermometer is generally from –10°C to 110°C

Questions: Why does the mercury not fall or rise in a clinical thermometer when taken out of the mouth?

Kink prevents mercury level from falling on its own.

Questions: What is conduction?

Heat flows from a hotter object to a colder object. The process by which heat is transferred from the hotter end to the colder end of an object is known as conduction.

Questions: Why conduction is only possible in solids

In solids, generally, the heat is transferred by the process of conduction because particles of solids are closely packed and heat is transferred from the hotter end to the colder end of an object.

Questions: What are conductor and insulators?

The materials which allow heat to pass through them easily are conductors of heat. For examples, aluminum, iron and copper

The materials which do not allow heat to pass through them easily are poor conductors of heat known as insulators such as plastic and wood.

Questions: Explain how water heated by convection?

The water is  poor conductors of heat so do not heated by conduction.

When water is heated, the water became lighter. Hot water rises up. The cold water from the sides moves down towards the source of heat  This water also gets hot and rises and water from the sides moves down. This process continues till the whole water gets heated. This mode of heat transfer is known as convection

Questions: What is land and sea breeze explain?

During the day, the land gets heated faster than the water. The air over theland becomes hotter and rises up. The cooler air from the sea rushes in towards  the land to take its place. The warm air from the land moves towards the sea to complete the cycle. The air from the sea

is called the sea breeze.

At night  , The water cools down more slowly than the land. So, the cool air from the land moves towards the sea. This is called the land breeze

Questions: How does the heat from the sun reach us?

It cannot reach us by conduction or convection as there is no medium such as air in most part of the space between the earth and the sun. From the sun the heat comes to us by  another process known as radiation.

Radiation can take place whether a medium is present or  not.

Questions: In summer we prefer light-coloured clothes and in winter we usually wear dark-coloured clothes. Why

Dark surfaces absorb more heat and, therefore, we feel comfortable with dark coloured clothes

in the winter. Light coloured clothes reflect most of the heat that falls on them and, therefore, we feel more comfortable wearing them in the summer.

Questions: How Woolen clothes keep us warm in winter

Woollen clothes keep us warm during winter. It is so because wool is a poor conductor of heat and it has air trapped in between the fibres

Questions: Why one thick blanket  is less warm up than  two thin blankets joined together?

There ia  a layer of air in between the blankets..Since air is bad conductor of heat preventbody heat to escape out.

Questions: Why we wear light cloths in summer?

Dark-coloured objects absorb radiation better than the light-coloured  objects. That is the reason we feel more comfortable in light-coloured clothes in the summer

Questions: What is the unit of heat

Units of Heat

(a) C.G.S. unit of heat is Calorie.

(b) The M.K.S. or S.I. unit of heat is Joule

1 calorie equals 4.18 or 4.2 joules approximately.

Questions: State similarities between the laboratory thermometer and the clinical thermometer

1. Laboratory thermometer and the clinical thermometer consist of a long, narrow, uniform glass tube.

2. Laboratory thermometer and the clinical thermometer have a bulb containing mercury at the end of the tube.

3. Laboratory thermometer and the clinical thermometer are marked with Celsius scale on the glass tube.

Questions: Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

In between the layers of cloths there is trapped air. As air is bad conductor of heat so the out side low temperature do not get transferred to body as well as prevent our body heat to escape out side. Hence more layers of cloths keep us warmer during cold winter.

Questions: In places of  hot climate it is advised that the outer walls of houses be painted white. Explain.

In places of  hot climate it is advised that the outer walls of houses be painted white because a light colour absorb very less radiant heat  and we feel comfortable inside such houses due to lower temperature inside house.

Questions: Why stainless steel cooking utensils  are usually provided with copper bottoms?

The reason for this could be that  copper is the best conductor of heat than the stainless steel.