16. During the growth of animal cells in culture, it is noticed that the cells do not look very healthy. After an investigation, this is found that there is a lot of lactic acid in the culture fluid. What is probably wrong with this culture?

A. Ethyl alcohol is being produced in excess
B. The cells have too much oxygen
C. Glycolysis is being inhibited
D. The cells do not have enough oxygen

17. The range of optimum glutamine concentration present in the culture media is

A. 1-2 mmol/litre
B. 2-7 mmol/litre
C. 7-15 mmol/litre
D. 15 – 20 mmol/litre

18. The human fibroplast is a classical example of

A. stable primary cell lines
B. established cell lines
C. cell transformations
D. none of these

19. pH of culture medium is initially controlled by

A. presence of CO₂
B. presence of bicarbonate buffer
C. addition of bases
D. none of these

20. Which of the following abnormality, resulted from the inheritance of an unbalanced complement of chromosomes that can be diagnosed through karyotyping?

A. Down’s syndrome
B. Turner’s syndrome
C. Klinefelter’s syndrome
D. all of these