Insectivorous plants grow in the soil which is deficient in:
1.  Mg
2.  Ca
3.  P
4.  N

When the plants are grown in magnesium-deficient but urea-rich soil, the symptoms expressed are:

1. Yellowish leaves

2. Colourless petiole

3. Dark green leaves

4. Shoot apex die

Plants deficient in the element zinc show its effect on the biosynthesis of which plant growth hormone:

Grey spots of oat are caused by deficiency of:

1. Cu

2. Zn

3. Mn

4. Fe