Class 7 Science - Chapter Soil NCERT Solutions | Solve the following crossword puzzle wit

Sketch the cross section of soil and label the various layers.

Match the items in Column I with those in Column II:
Column I                                              Column II
(i) A home for living organisms         (a) Large particles
(ii) Upper layer of the soil                 (b) All kinds of soil
(iii) Sandy soil                                   (c) Dark in colour
(iv) Middle layer of the soil                (d) Small particles and packed tight                                                                                                                                               (v) Clayey soil                                  (e) Lesser amount of humus

How is clayey soil useful for crops?

List the differences between clayey soil and sandy soil.

Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.

Explain how soil is formed.

In addition to the rock particles, the soil contains

(i) air and water
(ii) water and plants
(iii) minerals, organic matter, air and water
(iv) water, air and plants

Explain how soil pollution and soil erosion could be prevented.

The water holding capacity is the highest in

(i) sandy soil
(ii) clayey soil
(iii) loamy soil
(iv) mixture of sand and loam

State similarities and differences between the laboratory thermometer and the clinical thermometer.

State differences between acids and bases.

Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food

Name the elements that determine the weather of a place.

Fill the missing word in the blank spaces in the following statements:

(a) Wind is——————air.
(b) Winds are generated due to —————— heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of ——— pressure to a region of ———.

Why does an athlete breathe faster and deeper than usual after finishing the race?

Match structures given in Column I with functions given in Column II.

Column I                           Column II
(i) Stomata                        (a) Absorption of water
(ii) Xylem                           (b) Transpiration
(iii) Root hairs                    (c) Transport of food
(iv) Phloem                        (d) Transport of water
                                          (e) Synthesis of carbohydrates

Fill in the blanks:

(a) Production of new individuals from the vegetative part of parent is called_____________.
(b) A flower may have either male or female reproductive parts. Such a flower is called_____________.
(c) The transfer of pollen grains from the anther to the stigma of the same or of another flower of the same kind is known as _____________.
(d) The fusion of male and female gametes is termed as _____________.
(e) Seed dispersal takes place by means of _____________, _____________ and _____________.

Classify the following as motion along a straight line, circular or oscillatory motion:

(i) Motion of your hands while running.
(ii) Motion of a horse pulling a cart on a straight road.
(iii) Motion of a child in a merry-go-round.
(iv) Motion of a child on a see-saw.
(v) Motion of the hammer of an electric bell.
(vi) Motion of a train on a straight bridge.

Why do organisms need to take food?

What is a virtual image? Give one situation where a virtual image is formed.

Mark ëTí if the statement is true and ëFí if it is false:

(i) During heavy exercise the breathing rate of a person slows down. (T/F)
(ii) Plants carry out photosynthesis only during the day and respiration only at night. (T/F)
(iii) Frogs breathe through their skins as well as their lungs. (T/F)
(iv) The fishes have lungs for respiration. (T/F)
(v) The size of the chest cavity increases during inhalation. (T/F)

Given below is a square of letters in which are hidden different words related to respiration in organisms. These words may be present in any direction ó upwards, downwards, or along the diagonals. Find the words for your respiratory system. Clues about those words are given below the square.

(i) The air tubes of insects
(ii) Skeletal structures surrounding chest cavity
(iii) Muscular floor of chest cavity
(iv) Tiny pores on the surface of leaf
(v) Small openings on the sides of the body of an insect
(vi) The respiratory organs of human beings
(vii) The openings through which we inhale
(viii) An anaerobic organism
(ix) An organism with tracheal system

Given below is a crossword puzzle based on this lesson. Use hints to fill in the blank spaces with letters that complete the words.
Down                                               Across
(D) 1 : Thorough washing           (A) 1 : Keeps warm
      2 : Animal fibre                            2 : Its leaves are eaten by silkworms
      3 : Long thread like structure      3 : Hatches from egg of moth

Fig. 13.15 shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?

                           Fig. 13.15 Distance-time graph for the motion of two cars

Which of the following distance-time graphs shows a truck moving with speed which is not constant?

Classify the changes involved in the following processes as physical or chemical changes:
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f ) Digestion of food

Why do organisms need to take food?

Describe the function of the heart.

Explain the difference between self-pollination and cross-pollination.