How do the pollen grains of Vallisneria protect themselves? 

Name the respective pattern of inheritance where F1 phenotype

(a) does not resemble either of the two parents and is in between the two.

(b) resembles only one of the two parents.

Write the name of the following: 

(a) The most common species of bees suitable for apiculture

(b) An improved breed of chicken

4.

Mention the role of cyanobacteria as a biofertiliser. 

How is the entry of only one sperm and not many ensured into an ovum during fertilisation in humans? 

Where is acrosome present in humans? Write its function. 

State the significance of Coelacanth in evolution. 

Why is it desirable to use unleaded petrol in vehicles fitted with catalytic converters?

(a) Where do the signals for parturition originate from in humans?

Given reasons for the following: 

(a) The human testes are located outside the abdominal cavity.

(b) Some organisms like honey-bees are called parthenogenetic animals.