Water: A Precious Resource — Science STD 7 — Question

The raw and baked soil differs from each other. How they are different? How can you prepare matkas from soil?

Explain what you understand by sexual reproduction.

Mention the benefits of seed dispersal.

A farmer was unhappy because of his low crop yield. He discussed the problem with an agricultural scientist and realised that the soil of his field was either too acidic or too basic. What remedy would you suggest the farmer to neutralise the soil?

What is symbiosis? Explain with an example.

Explain the following.

1. Copper and aluminium wires are usually employed for electricity transmission. Explain the reason.
2. Explain how does the resistance of a wire vary with its length.
3. The tungsten is used almost exclusively for filament of electric lamp. Comment.

Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

One day Rahul's mother after taking meal felt pain and irritation in her stomach at that time his father was out of station. Rahul remembered his teacher's statement and gave his mother some baking soda solution which gave her a relief from pain and irritation in stomach.
Read the above passage and answer the following questions
(i) Which information given by Rahul's teacher, that helped him to select the baking soda as remedy?
(ii) Why did he select baking soda as a cure?
(iii) What values are shown by Rahul?

What planning is required in advance to deal with the situation created by a cyclone?

Recall and name the main organs of the digestive system in our body.