Prepare for NEET with Botany-specific practice questions. Covering all major Botany chapters, this is perfect for your NEET Biology needs.
A transgenic mouse expressing a human growth hormone gene exhibits gigantism. Researchers discover a second transgenic mouse line with the same human growth hormone gene construct, yet these mice show normal growth. Which of the following is the MOST LIKELY explanation for this discrepancy?
The second mouse line has a mutation in the mouse growth hormone receptor gene.
The human growth hormone gene is not being transcribed in the second mouse line.
Position effect variegation due to the transgene's insertion site in the second mouse line.
The second mouse line expresses an endogenous inhibitor of human growth hormone.
Knockout mice lacking the gene for PrP (prion protein cellular form) are resistant to prion diseases. What can be directly concluded from this observation?
PrP is sufficient to cause prion diseases.
PrP is the infectious agent in prion diseases.
PrP is necessary for the development of prion diseases.
The absence of PrP enhances the immune response against prions.
A transgenic animal is created by inserting a gene for enhanced muscle growth into its genome. However, the resulting offspring show a variety of phenotypes, some with significantly enhanced muscle growth, others with moderate enhancement, and some with no change at all. Which phenomenon is MOST likely responsible for this phenotypic variation?
Incomplete penetrance of the transgene
Pleiotropic effects of the transgene
Variable transgene copy number and integration sites
Epigenetic silencing of the transgene in some individuals
A researcher is studying phloem transport in a plant using radioactive . After introducing the radioisotope to a mature leaf, where would the LEAST radioactivity be detected after a short period?
Apical meristem
Young developing leaves
Roots
Mature leaf cells lacking plasmodesmatal connections to the phloem
Which condition would MOST significantly inhibit the translocation of sucrose in phloem?
Decreased sucrose concentration in source cells
Increased sucrose concentration in sink cells
Application of a metabolic inhibitor that blocks ATP synthesis in companion cells
Exposure to light
A plant exposed to a fungal toxin exhibits significantly reduced translocation of potassium ions () despite normal transpiration rates. The toxin MOST likely affects which process?
Stomatal opening and closing
Water potential gradient in the xylem
Activity of membrane transport proteins involved in uptake into xylem
Root pressure generation
Researchers observed that inhibiting phloem unloading in a developing fruit resulted in a decrease in sucrose transport to that fruit. However, the transport of certain amino acids to the fruit was unaffected. Which explanation is MOST likely?
Amino acids are transported through the xylem, not the phloem.
Amino acid transport is solely driven by diffusion, unaffected by phloem unloading mechanisms.
Amino acids and sucrose share the same transporters, but amino acids have a higher affinity.
Amino acids are unloaded via a different mechanism than sucrose, potentially utilizing specific transporters independent of sucrose unloading.
A scientist is attempting to develop a novel gene therapy for cystic fibrosis. They are utilizing a modified adeno-associated virus (AAV) vector to deliver the functional CFTR gene. However, pre-clinical trials show limited efficacy due to pre-existing neutralizing antibodies against the AAV capsid in a significant portion of the target population. Which of the following strategies would be MOST effective in overcoming this limitation?
Increasing the dosage of the AAV vector.
Administering immunosuppressants prior to gene therapy.
Engineering AAV capsids with altered surface epitopes to evade pre-existing immunity.
Switching to a lentiviral vector delivery system.
A patient exhibits severe combined immunodeficiency (SCID) due to a deficiency in adenosine deaminase (ADA). Which gene therapy approach is MOST likely to provide a long-term solution?
In vivo gene therapy using a retroviral vector directly injected into the bone marrow.
Administering purified ADA enzyme intravenously.
Ex vivo gene therapy using autologous hematopoietic stem cells.
Bone marrow transplant from an HLA-matched sibling.
A deep-sea hydrothermal vent ecosystem relies entirely on chemosynthetic bacteria as primary producers. If 1000 kJ of energy is fixed by these bacteria, approximately how much energy would be available to a tertiary consumer, assuming a 10% ecological efficiency at each trophic level?
1 kJ
10 kJ
100 kJ
1000 kJ
