Question

26) When oxygen is not available as a final electron acceptor, human cells go through fermentation. What is the disadvantage to this process in humans?
    A. Significantly less ATP is extracted from glucose.        B. Ethanol is a byproduct.
    C. Our genes can become mutated.            D. Mitochondria degrade in lysosomes.

27) Why is the signal transduction pathway necessary?
A. This is how viruses are inactivated by T lymphocytes.
B. It is necessary to get bacteria to make proteins for medical purposes.
C. Some messages (growth factors) are proteins which cannot get through the cell membrane to deliver the message directly to DNA.
D. Some cells which should go through apoptosis ignore the message.
   
28) Which of the following genes is a tumor suppressor gene and is carried by both men and women?  
        A. OVA 3        B. huntingtin        C. BRCA1        D. ABCR

Answer 1

26) By fermentation process, the amount of ATP generated is far much less than that is generated by respiration using oxygen as the final electron acceptor.

Process	Number of ATP/glucose molecule
Aerobic Respiration	38
Fermentation	2

Although Ethanol is an end product in fermentation, it can be neutralised by the enzymes such as alcohol dehydrogenase which convert it into less toxic forms and our genes doesn't get mutated and mitochondria is not getting degraded in lysosomes because of fermentation process that occurs we when deprived of oxygen.

Answer: A. Significantly less ATP is extracted from glucose

27. Some of the messenger molecles such as growth factors cannot pass through the lipid bilayer of the plasma membrane all the way into the cell due to their hydrophilic nature. So, it binds to its receptors in the cell membrane, thereby transferring the message it carries to the target sit (DNA) in the cell via signal transduction pathways comprising secondary messengers and other regulatory proteins.

While the other options are less significant for cell survival although signal transduction is employed in some of these processes and a cell doesn't ignore message for apoptosis and is largely driven by intracellular activities.

Answer: C. Some messages (growth factors) are proteins which cannot get through the cell membrane to deliver the message directly to DNA.

28. The tumour suppressor genes that are carried by both men and women are

Gene	Function
OVA3	codes for glutamate tRNA synthetase
huntingtin	This gene linked to a neurodegenerative disorder in humans called Huntington's disease
BRCA1	It encodes a nuclear phosphoprotein which along with other tumour suppressors and DNA damage sensors maintain the genomic stability. It is expressed in both males and females in human
ABCR	Codes for a membrane associated protein belonging to ATP binding casette transporters superfamily

Therefore, BRCA1 is the only gene in the given option that is present in both males and females and involves in tumour suppression

Answer: C. BRCA1