Nutrition in Plants — Science STD 7 — Question

We often find green slimy layers on the surface of ponds. The layers are formed by tiny organisms that make their own food. Which of these is/are true about the organisms?
Circle 'Yes' or 'No' in each row.Circle 'Yes' or 'No' in each row.

Is the statement about the organisms true?	Yes/No
(a) They contain chlorophyll.	Yes/No
(b) They release oxygen.	Yes/No
(c) They require sunlight for making food.	Yes/No

Condensation of steam is chemical process or physical change?

What is the role of chlorophyll?

In a mercury thermometer, the level of mercury rises when its bulb comes in contact with a hot object. What is the reason for this rise in the level of mercury?

Trisha has seen huge garbage dumps outside the school campus which are not being regularly disposed off by municipality of the area. She discussed the problem with her biology teacher and decided to organise a rally to spread awareness among local people. Next day she delivered this information in the assembly and convinced the school mates to join her. She also explained them about the importance of sanitation at public places which she had recently studied in biology.
(i) In your views, who is responsible to maintain sanitation at public places?
(ii) What would happen, if all the wastes produced at public places are not disposed off regularly?

What is circular motion?

What is the reason behind floating of ice in water?

State whether the following statement are true or false. Correct the false statement. Lemon water is basic in nature.

Give an example of a chemical reaction for each of the following situation: Sound is produced.

How are oxygen and food circulated in Hydra?