Diatoms have left behind large amounts of cell wall deposits in their habitat because:

1. They are most abundant in that habitat

2. Their life span is long 

3. Their wall is indestructible

4. The statement is not true

Members of Kingdom Protista:

1. are primarily aquatic 

2. do not have membrane bound organelles

3. are all ciliated or flagellated

4. reproduce exclusively by asexual means

Select the wrong statement.

(1) The walls of diatoms are easily destructible

(2) 'Diatomaceous earth' is formed by the cell walls of diatoms

(3) Diatoms are chief producers in the oceans

(4) Diatoms are microscopic and float passively in water

In which group of organisms the cell walls form two thin overlapping shells which fit

together?

1. Chrysophytes

2. Euglenoids

3. Dinoflagellates

4. Slime moulds

Diatoms do not decay easily because

1. they have siliceous walls

2. their body is impervious to water

3. they are chitinous

4. they are abundant in saline soil