Give two differences each between :
(i) Active absorption and Passive absorption
(ii) Transpiration and Guttation.
Functions of the placenta in mammals
i. Placenta helps to transport nutrients from maternal blood into foetus
ii. It helps in getting oxygen from the maternal blood into the foetus and CO2 from foetus blood into the maternal blood.
iii. Nitrogenous waste products produced in the embryo diffuse through the placenta into the maternal blood stream.
iv. Antibodies developed in the mother against certain diseases like measles, small pox, diphtheria pass from mother into the foetal blood through the placenta.
viPathogenic organisms like viruses diffuses through the placenta. Viruses causing syphilis, measles, rubella, small pox may infect the foetus, if the mother gets the disease during pregnancy. Some of these diseases may even cause congenital deformities.
Some of the drugs taken by the mother during pregnancy cross the placental barrier and may even cause developmental deformities.