Frank Cce Everyday Science Solutions for Class 7 Science Chapter 23 Summative Assessment 1 are provided here with simple step-by-step explanations. These solutions for Summative Assessment 1 are extremely popular among class 7 students for Science Summative Assessment 1 Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Frank Cce Everyday Science Book of class 7 Science Chapter 23 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Frank Cce Everyday Science Solutions. All Frank Cce Everyday Science Solutions for class 7 Science are prepared by experts and are 100% accurate.

Page No 138:

Question A.1:

Why does pitcher plant traps insects?

Answer:

A pitcher plant traps insects to extract nutrients from them that are not present in the soil. The plant grows on soils that are deficient in nitrogenous compounds. To compensate for the lack of nitrogen, the pitcher plant derives it from the insects it traps.

Page No 138:

Question A.2:

How does dodder absorbs its food from its host plant?

Answer:

A dodder uses specially adapted sucking roots known as haustoria that absorb nutrients from the host it grows upon.

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Question A.3:

What do you mean by symbiosis?

Answer:

Symbiosis is an association between two organisms from which they mutually benefit. For example, lichens are formed by an association between algae and fungi. The algae provide food to fungi by photosynthesis, while the fungi provide shelter and water to algae.

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Question A.4:

What is sericulture?

Answer:

Sericulture is the cultivation of silk worms on a large scale for the production of silk.

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Question A.5:

What happens to radiant heat when it falls on a body?

Answer:

When radiant heat falls on a body, some of the heat is reflected and some absorbed heating up the body. Some of the heat is also conducted through the body.

Page No 138:

Question A.6:

How do fungi absorb their food?

Answer:

Fungi release thin strands known as hyphae through the material they grow in. The hyphae then release enzymes that break down the substrate and allow the fungi to absorb their food.

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Question A.7:

Why is scouring of wool done?

Answer:

Wool is scoured to remove dust, dirt and grease.

Page No 138:

Question A.8:

What is weathering of rock?

Answer:

The erosion and breakdown of large pieces of rock into soil by the action of wind, rain, sun, plants and microorganisms is known as weathering.

Page No 138:

Question B.1:

Explain how liquids and gases are heated.

Answer:

Liquids and gases are both fluids. They get heated by the process of convection. The molecules of the fluid move physically from the hotter to the cooler regions, causing heat to flow from the hot to the cold region, until the entire fluid gets heated up.

Page No 138:

Question B.2:

What is an indicator? Give two examples along with their action in acids and bases.

Answer:

An indicator is a substance that changes it colour, depending on whether it is added to an acid or a base.
Examples of indicators are:

  1. Litmus paper: Blue litmus paper turns red in the presence of an acid, while red litmus turns blue in the presence of a base.
  2. Turmeric: It is a natural indicator that turns yellow in the presence of an acid and red in the presence of a base.

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Question B.3:

What is crystallisation and in what way is the process useful to us?

Answer:

Crystallisation is the process of formation of solidified crystals from a super saturated solution of that solid in a suitable solvent. It is a useful process as it helps in isolating crystals of very high purity, particularly if the solid contains impurities.

Page No 138:

Question B.4:

Why room heater have polished reflector at the back?

Answer:

A room heater has a polished reflector at the back because of the following reasons:

  1. The reflector will reflect heat to the front of the heater so that more heat would be available at the front of the heater.
  2. The polished surface avoids excessive heat absorption by the heater, and thus prevents a fire hazard.

Page No 138:

Question B.5:

Define soil pollution. Mention any four causes.

Answer:

Soil pollution is defined as the contamination of soil by pesticides, herbicides, insecticides, industrial wastes, dumping of garbage, etc.
Following are the causes of soil pollution:

  1. Excessive use of chemical fertilizers, pesticides, weedicides and herbicides in agriculture
  2. Unchecked release of sewage or wastes into the soil
  3. Industrial chemical wastes being discharged directly into the soil
  4. Contamination of soil by non-biodegradable wastes such as plastics, metals, etc.

Page No 138:

Question C.1:

How do weathering of rocks occur?

Answer:

Weathering is the process of breakdown of bigger rocks into smaller mineral particles.
 It can occur by the following methods:
(i) Physical weathering: It occurs because of climatic factors such as temperature, wind, rain water, ice and snow.
(ii) Chemical weathering: It occurs through chemical processes such as hydrolysis, hydration, oxidation and reduction.
(iii) Biological weathering: It is carried out by living organisms such as lichens and bryophytes.

Page No 138:

Question C.2:

How would you show that chlorophyll is necessary for photosynthesis?

Answer:

Take a variegated leaf (that is, a leaf that is partly green and partly white) of a croton plant that was kept in sunlight for a few hours. The green parts of the leaf contain chlorophyll, whereas the white portion does not. Immerse the leaf into boiling water and let it boil for a few minutes, such that the cells in the leaf are killed. Now, to decolourise the leaf, boil it in rectified spirit. Wash the decolourised leaf in hot water so as to remove any chlorophyll sticking to it. Place the leaf in dilute iodine solution.

We observe the parts of the leaf which were green turn blue-black in colour, showing the presence of starch in those areas. The parts of the leaf which were white does not change colour, showing that no starch is present in these portions of the leaf.

This shows that chlorophyll is essential for photosynthesis, as only the green portion of the leaf contained starch.

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Question C.3:

How do land and sea breeze occur?

Answer:

Formation of sea breeze:
During day time, land gets heated faster than the sea water. On the one hand, heated air rises up, creating a temporary low pressure region and this draws cold air from the sea towards it. This happens because land surface absorbs and radiates heat readily because it has low specific heat capacity. On the other hand, liquid gets heated up slowly and radiates the heat in it at a slower rate, as it has a very high specific heat capacity. This breeze blowing from the sea towards land is called sea breeze.

Formation of land breeze:
During the night, as land loses its heat quickly, it cools faster than sea water. However, the surface of the sea is still hot, as it loses heat slowly. Therefore, the hot air above the sea rises up and cold air from the land moves towards the sea. This breeze blowing from the land to the sea is called land breeze.

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Question C.4:

Why is loamy soil considered best for agriculture?

Answer:

Loamy soil is considered the best soil for agriculture as it has the following properties:
1. Good water-holding capacity
2. Sufficient aeration
3. Sufficient mineral salts
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