What are sex hormones? Why are they named so? State their function.
The chemical substances produced by sex organs are called sex hormones. For example:
Sex hormones affects the sexual features of an organism. So, they named as sex hormones. Sex hormones play a important role in our body. Some of the function of sex hormones are as follows:
Testosterone: It is the male sex hormone. It is responsible for secondary sexual characters in male body like growth of beard, developing of reproductive organs and the voice becomes hoarse etc.
Oestrogen: It is the female sex hormone. It is responsible for the secondary sexual characters in the female body like increase in the size of breast, voice becomes soft, development of reproductive organs etc.
Describe with the help of a diagram an instrument which can be used to detect a charged body.
Sketch larynx and explain its function in your own words.
What is metamorphosis? Give examples.
Make a labelled diagram of a candle flame.
The following Table shows the total power shortage in India from 1991– 1997. Show the data in the form of a graph. Plot shortage percentage for the years on the Y-axis and the year on the X-axis.
Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
Make sketches of animal and plant cells. State three differences between them.
What is a constellation? Name any two constellations.
Describe the construction of a kaleidoscope.
Make a sketch of the human nerve cell. What function do nerve cells perform?
Complete the crossword with the help of clues given below:
Across
1. This is necessary for photosynthesis.
3. Term for component present in the cytoplasm.
6. The living substance in the cell.
8. Units of inheritance present on the chromosomes.
Down
1. Green plastids.
2. Formed by collection of tissues.
4. It separates the contents of the cell from the surrounding medium.
5. Empty structure in the cytoplasm.
7. A group of cells.
Which part of the cell contains organelles?
What is metamorphosis? Give examples.
Describe an activity to show that the incident ray, the reflected ray and the normal at the point of incidence lie in the same plane.
What is menstruation? Explain.
Match items in column A with those in column B.
A B
(i) Kharif crops (a) Food for cattle
(ii) Rabi crops (b) Urea and super phosphate
(iii) Chemical fertilisers (c) Animal excreta, cow dung urine and plant waste
(iv) Organic manure (d) Wheat, gram, pea
(e) Paddy and maize
How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm?
Make sketches of animal and plant cells. State three differences between them.
Explain why objects moving in fluids must have special shapes.
Write short notes on the following:
(a) Cytoplasm
(b) Nucleus of a cell