Winds, Storms and Cyclones — Science STD 7 — Question

List some animals found in your locality and categorise them into following groups.
(i) Animals that excrete ammonia in gaseous forms.
(ii) Animals that excrete uric acid in the form of pellets.
(iii) Animals that excrete urea in the form urine.

One day, Ramesh’s friend was performing their respective experiments given by their teacher. While sitting in the practical lab instead of performing experiment, Ramesh was playing with his meter scale. All the sudden, he held the scale in his hand and started moving in front of tubelight, then he observed the seven colours of white light. After sometimes, he got scolded by his lab teacher for not performing the experiment.

1. Give the name of phenomenon that leads to the formation of band of seven colours.
2. Name the constituent colours of white light.
3. Mention the values shown by Ramesh here.

The smallest time interval that can be measured with commonly available clocks and watches is one second. However, special clocks are available that can measure time intervals smaller than a second. Some of these can measure time intervals as small as one millionth or even one billionth of a second.
1. A micro-second is a very small time interval. Write its value in fraction of a second.
2. Define time period.
3. What is the basic unit of time?

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

Draw a figure showing two animals, two birds and a few trees as a part of a forest.

Explain why there is no waste in a forest.

Paheli uprooted a rose plant from the soil. Most of the root tips, with root hairs got left behind in the soil. She planted it in a pot with new soil and watered it regularly. Will the plant grow or die? Give reason for your answer

Harish went to visit his grandfather in village where he saw that his grandfather’s field of wheat are infected with fungus but no one is aware of this. Harish rushed to his grandfather’s side and told him that the field have been infected with fungi. He should use an antifungal agent in his fields to stop this infection.

1. What is fungus?
2. Can fungus only cause diseases or can it be helpful also?
3. What values are shown by Harish?

Observe the following figure and answer the following questions:

(i) What does this figure show?
(ii) Name the gas released.
(iii) Write the effect of the gas on lime water.
(iv) Write the chemical equation of the reaction.

What do you mean by reeling of silk?