21.
Consider the following statements and choose the correct answer:
1. The integuments of the ovule become dry and firm, the seed coat
2. Insoluble food is formed in the ovule as a result of dehydration
3. In endospermic seeds the insoluble food is stored in cotyledons
4. The ovary wall forms the fruit wall which may be hard or fleshy

25.
Except which of the following steps, in all other steps the pair of electrons, released in respiration, reduces NAD+ to NADH ?

26.
When the water is trickling downwards due to gravity, a portion of the water is retained around and between the soil particles due to surface tension. This water is known as

29.
Consider the following statements regarding tobacco mosaic viruses and choose the correct answer:
1. Tobacco mosaic viruses are sap transmissible
2. These can stand a high degree of dilution
3. Breaking of a hair with contaminated instrument serves as a means of transmitting the virus
4. These viruses are insect borne