The Fundamental Unit of Life — Science STD 9 — Question

‘X’ and ‘Y' are two elements which form X₂Y₃ and X₃Y₄. If 0.2mol of X₂Y₃ weighs 32g and 0.4mol of X₃Y₄, weighs 92.8g, the atomic weights of X and Y respectively are:

Several embryos can be produced at a time in a single cow by the process of:

1. Hybridization.
2. Artificial insemination.
3. Embryo transfer.
4. Random mating.

Mitochondria are seats of:

1. Aerobic respiration.
2. Krebs cycle of aerobic respiration.
3. Glycolysis of aerobic respiration.
4. Anaerobic respiration.

(1) In uniform circular motion, tangential acceleration is zero (2)In uniform circular motion, velocity is constant.

Of the following components of phloem is non-living:

Time taken to complete one vibration is called:

Find out the correct sentence.

1. Hybridization means crossing between genetically dissimilar plants.
2. Cross between two varieties is called as inter-specific hybridization.
3. Introducing genes of desired characters into a plant gives genetically modified crop.
4. Cross between plants of two species is called as inter varietal hybridization.

1. (i) and (ii)
2. (ii) and (iv)
3. (ii) and(iii)
4. (iii) and (iv)

Duck-billed platypus and echidna are:

1. Reptiles.
2. Egg-laying marnmals.
3. Marsupial mammals.
4. Eutherian mammals.

The method of incorporating desirable qualities in crop varieties is:

Which of the following vibrates when a musical note is produced by the cymbals in an orchestra?

1. Stretched strings.
2. Stretched membranes.
3. Metal plates.
4. Air columns.