Question 1: Sex determination refers to the biological system that decides whether an organism develops as male or female. It can be influenced by genetic factors or environmental conditions. Understanding these mechanisms helps explain variations in reproductive biology among different species.

Answer: Sex determination is the biological process that decides the sex of an organism, influenced by genetic factors like chromosomes or environmental factors such as temperature.

Question 1: Define the term 'chromosomal sex determination'.

Answer: Chromosomal sex determination is a mechanism where the sex of an organism is determined by its specific set of sex chromosomes.

Question 2: Which chromosomes typically determine the sex in humans?

Answer: XY

Question 3: Describe how the presence of the Y chromosome influences male development.

Answer: The Y chromosome carries the SRY gene which triggers the development of testes and male characteristics during embryonic development.

Question 1: Name an organism in which temperature influences sex determination.

Answer: Some species of turtles and crocodiles.

Question 2: Explain how temperature can affect the sex of developing embryos in such species.

Answer: In species with temperature-dependent sex determination, the temperature during a critical period of embryonic development influences the sex. For example, higher temperatures may produce males, while lower temperatures produce females, depending on the species' specific temperature thresholds.

Question 1: In a population of 1000 turtles with temperature-dependent sex determination, 600 develop as males. What is the ratio of males to females?

Answer: Males: 600, Females: 400; Ratio of males to females = 600:400 = 3:2.

Question 1: Describe a method scientists might use to determine the sex of an organism at an early developmental stage without visual examination.

Answer: Scientists can analyse the organism's genetic material, such as detecting sex-specific chromosomes or genes using molecular techniques like PCR.

Question 2: Discuss how understanding sex determination mechanisms can aid in the conservation of endangered species.

Answer: Understanding sex determination helps conservationists manage breeding programmes by ensuring a balanced sex ratio, which is crucial for population sustainability. It can also assist in developing techniques to control sex ratios in captive breeding to increase the number of breeding individuals.