Carbon and its Compounds — Science STD 10 — Question

Describe the working of human blood circulatory system with the help of a suitable diagram which shows all the steps involved.

1. Name the organs that form the excretory system in human beings.
2. Describe in brief how urine is produced in human body.

1. Draw a ray diagram to show the formation of image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.
2. In the above ray diagram mark the object-distance (u) and the image-distance (v) with their proper signs (+ve or – ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.
3. Find the power of a convex lens which forms a real, and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.

Name the four main stakeholders in the management of forest resources.

In a village, farmers started cultivating crops all around a lake which was always filled with water. They added lot of materials W to the soil in their fields to increase the yield of crops. Soon they found that the whole surface of water in the lake was covered with a green layer made up of tiny organisms X. After some time, the fish present in the lake started dying in large numbers because they could not get sufficient Y due to a process Z which had occurred in lake water and drained out all the Y present in the water of lake.

1. What do you think materials W are?
2. Name (i) X, and (ii) Y?
3. What is the process Z known as?
4. What happens during the process Z which uses up all the Y present in lake water?
5. What does this example tell us about the use of materials like W?

What is a decomposition reaction? Give an example of a decomposition reaction. Describe an activity to illustrate such a reaction by heating.

What are reflex actions? Give two examples. Explain a reflex arc.

When a moist slice of bread was kept aside for a few days then some organism grew on it to form a white cottony mass which later turned black. When this slice of bread was observed through a magnifying glass, then fine thread-like projections and thin stems having bulb-like structures at the top were seen.

1. What is the common name and scientific name of the organism which grew on the moist slice of bread?
2. How did this organism grow on the moist slice of bread automatically?
3. What are the fine, thread-like projections on the surface of slice of bread known as?
4. What name is given to the knob-like structures and what do they contain?
5. What is the name of this method of reproduction?
6. Name one unicellular organism which reproduces by this method.
7. Name tow non-flowering plants which reproduce by this method.

1. Draw a longitudinal section of a flower and label the following parts:

1. Part that produces pollen grain.
2. Part that transfers male gametes to the female gametes.
3. Part that is sticky to trap the pollen grain.
4. Part that develops into a fruit.

2. Differentiate between pollination and fertilisation.