Oxygen liberated during photosynthesis comes from

The blood leaving the tissues becomes richer in

$(a)$ Draw the structure of a nephron and label the following parts on it:
$(i)$ Renal artery
$(ii)$ Bowman's capsule
$(iii)$ Glomerulus
$(iv)$ Collecting duct
$(b)$ Name four substances in the initial filtrate which are selectively reabsorbed as the filtrate flows along the tubule.

Which is the first enzyme to mix with food in the digestive tract?

Which of the following statement$(s)$ is/are true about the heart?

Name the process of loss of water in the form of vapour from the aerial parts of the plants.