Photo AI
Protection, nourishment and gaseous exchange are important requirements for the successful development of an embryo - NSC Life Sciences - Question 4 - 2018 - Paper 1
Question 4
Protection, nourishment and gaseous exchange are important requirements for the successful development of an embryo. Describe how gaseous exchange and the nourishme... show full transcript
Worked Solution & Example Answer:Protection, nourishment and gaseous exchange are important requirements for the successful development of an embryo - NSC Life Sciences - Question 4 - 2018 - Paper 1
Step 1
Gaseous exchange in amniotic eggs (A)
Answer
Gaseous exchange in amniotic eggs occurs primarily through diffusion. The gases move in and out of the egg through the porous shell, also known as the allantois or chorion. This allows essential gases to enter the egg while enabling waste gases such as carbon dioxide to exit.
Step 2
Nourishment of the embryo in amniotic eggs (B)
Answer
In an amniotic egg, nourishment is provided by the yolk, which contains nutrients critical for the developing embryo. The albumin also plays a role in supplying additional nutrients, ensuring the embryo has adequate resources for development.
Step 3
Gaseous exchange and nourishment of the foetus in humans (C)
Answer
In humans, gaseous exchange and nourishment occur in the placenta. The mother's blood comes into close contact with the foetal blood, allowing oxygen and nutrients to diffuse from the mother's blood into the foetal blood. This nutrient-rich blood is then carried to the foetus through the umbilical cord, while carbon dioxide diffuses out of the foetus into the maternal blood.
Step 4
Protection of the foetus in humans (D)
Answer
The foetus develops inside the uterus and is protected by the mother's body. Antibodies from the mother provide immunity to the foetus. Additionally, the placenta acts as a microfilter, preventing toxins from entering the foetus's blood. The amniotic fluid surrounding the foetus also provides protection against dehydration and acts as a shock absorber, ensuring a stable environment and suitable temperature for the developing embryo.