Class 7 - Science - CH4 - Heat

NCERT Solution and Q & A

Q1: Define Heat.

Answer: Heat is a form of energy which produces a sensation of hotness or coldness. It is measured in Joules (J) or in Calories. Heat energy flows from one body to another due to temperature difference between the two. Heat is an internal energy of the substance due to molecular motion of the substance.

Class 7 - Science - CH3 - Fibre To Fabric

NCERT Chapter Solutions and Q & A

Sources of Wool
(image credits: openclipart.org)

Q1: You must be familiar with the following nursery rhymes:

(i) ‘Baa baa black sheep, have you any wool.’

(ii) ‘Mary had a little lamb, whose fleece was white as snow.’

Answer the following:

(a) Which parts of the black sheep have wool?

(b) What is meant by the white fleece of the lamb?

class 7 - Science - Ch6 - Physical and Chemical Changes

NCERT Solutions and other Q & A

Melting of Ice Cream (Physical Change)
(Source: openclipart.org)

Q1: What do you mean by physical properties of matter?

Answer: A physical property can be measured and observed without changing the composition or identity of a substance. E.g. Odour, colour, volume, state (gas, liquid, or solid), density, melting point, and boiling point are physical properties of a substance.

Q2: What do you mean by physical changes?

Answer: Physical changes are changes in the physical properties of substances. No new substances are formed in these changes. These changes may be reversible. E.g. melting of ice.

Class 7 - Science - Ch2 - Nutrition in Animals

NCERT Text book Solutions and other Questions and Answers

Q1: Fill in the blanks:
Answer: 
(a) The main steps of digestion in humans are ingestion, digestion, absorption , assimilation and egestion.

(b) The largest gland in the human body is liver.

(c) The stomach releases hydrochloric acid and digestive juices which act on food.

(d) The inner wall of the small intestine has many finger-like outgrowths called villi.

(e) Amoeba digests its food in the food vacuole .

Q2: Mark ‘T’ if the statement is true and ‘F’ if it is false:
Answer:
(a) Digestion of starch starts in the stomach. (T/F) : False. It starts in the mouth
(b) The tongue helps in mixing food with saliva. (T/F) : True
(c) The gall bladder temporarily stores bile. (T/F) : True
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F) : True

Q3: Tick (√) mark the correct answer in each of the following:
Answer:

(a) Fat is completely digested in the(i) stomach
(ii) mouth
(iii) small intestine  (√)
(iv) large intestine

(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) foodpipe
(iii) small intestine
(iv) large intestine (√)

Q4: Match the items of Column I with those given in Column II:
Answer:
Carbohydrates - Sugar
Proteins           - Amino acids
Fats                 - Fatty acids and glycerol

class 7 - Science - Ch1 - Nutrition in Plants

Nutrition in Plants

Q1: Why do organisms need to take food?

Answer: All organisms take food and utilise it to get energy for the growth and maintenance of their bodies.

Q2: Why do plants use the nitrogen present in soil? How is this nitrogen replenished in the soil?

Answer: Plants cannot absorb nitrogen in gas form; they need it in soluble form. Therefore, they use the nitrogen present in soil to prepare proteins.

Atmospheric nitrogen is fixed in soil by nitrogen-fixing bacteria such as Rhizobium,which live in the root nodules of leguminous plants such as gram, peas, beans, etc. In return, the plants provide food and shelter to the bacteria.

Explore Biodigital Human Body in 3D

The website BioDigitalHuman provides interactive 3D Human body and anatomical systems views.

To view the website you need a browser supports HTML5 and WebGL. Chrome supports these. I think you need to install plugins in Firefox and IE9+. You need a broadband connection to view the site. No doubt it has been the award winning site.

NTSE (SAT Quiz-3)

Q1: Which of the following is an antibiotic?
       a. Aspirin
       b. Penicillin
       c. Paracetamol
       d. Sulphadizine

Q2: Digestion of food starts in:
       a. mouth
       b. liver
       c. stomach
       d. intestines

Q3: By taking the pulse rate of the human body, a doctor determines
       a. heartbeat
       b. functioning of heart valves
       c. condition of lever
       d. functioning of lungs

Q4: A thermostat is used to
       a. purify air
       b. regulate humidity
       c. regulate temperature
       d. regulate air pressure

Q5: Heat from the sun reaches the earth by
        a. reflection
        b. conduction
        c. convection
        d. radiation

Q6: Dew forms most readily on nights that are:
        a. calm and clear
        b. stormy
        c. windy
        d. cloudy

Q7: The full moon rises in the
        a. east
        b. west
        c. south
        d. north

Q8: An aeroplane is able to fly because
       a. it is lighter than air
       b. it is heavier than air
       c. it is made up of very light material
       d. moving air can lift objects

Q9: The souring of milk is caused by the action of
        a. protozoan
        b. bacteria
        c. virus
        d. fungus

Q10. The smallest thing that can cause disease in the human body is
         a. flea
         b. bacteria
         c. protozoa
         d. virus

Q11: The most abundant gas in the air is:
         a. oxygen
         b. carbon dioxide
         c. nitrogen
         d. hydrogen

Q12: Which element is common between brass and bronze
         a. copper
         b. Iron
         c. Zinc
         d. Aluminium

Q13: The densest element known so far is
         a. gold
         b. mercury
         c. osmium
         d. tungsten

Q14: The most ductile element is
         a. gold
         b. silver
         c. iron
         d. aluminium

Q15: The metal having the highest melting point is
         a. chromium
         b. tungsten
         c. diamond
         d. Silver

Answers: 1-b     2-a     3-a     4-c    5-d     6-a     7-a    8-d    9-b    10-d

                11-c    12-a   13-c    14-a   15-b

See other quizes at link1, link2, link3

CBSE Class 7 - Science - Light - Questions & Answers

Class 7 - Ch 15 - Science - Light - Questions & Answers

Question1: Fill in the blanks
a. An image that cannot be obtained on a screen is called ______.

b. Image formed by a convex _______ is always virtual and smaller in size.

c. An image formed by a __________ mirror is always of the same size as that of the object.

d. An image which can be obtained on a screen is called a _________ image.

e. An image formed by a concave ___________ cannot be obtained on a screen.

Answers:
1 a) virtual image
b) convex mirror
c) plane
d) real
e) concave lens 

Question2: Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) We can obtain an enlarged and erect image by a convex mirror. (T/F)
(b) A concave lens always form a virtual image. (T/F)
(c) We can obtain a real, enlarged and inverted image by a concave mirror. (T/F)
(d) A real image cannot be obtained on a screen. (T/F)
(e) A concave mirror always form a real image. (T/F)

Answers: a-false b-true c-true d-false e-false

Class 7 - Science Chapter 15 - Light

 Class 7 - Science Chapter 15 - Light

1. Light travels along straight lines. This property is called rectilinear propagation of light.

2. Any polished or a shining surface acts as a mirror.

3. Change in direction of light from an object is called reflection of light.

4. An image which can be obtained on a screen is called a real image.

5. An image which cannot be obtained on a screen is called a virtual image.

6. The image formed by a plane mirror is erect. It is virtual and is of the same size as the object. The image is at the same distance behind the mirror as the object is in front of it.

7. In an image formed by a mirror, the left side of the object is seen on the right side in the image, and right side of the object appears to be on the left side in the image. This property is called Lateral Inversion.