Prepare for NEET with Botany-specific practice questions. Covering all major Botany chapters, this is perfect for your NEET Biology needs.
A plant is exposed to for a short period. After 5 minutes, the radioactive carbon is detected in the phloem sieve tubes near the source. After 20 minutes, it's found further down the stem in the phloem. Which observation MOST directly contradicts the mass flow hypothesis?
Sucrose moves bidirectionally in the phloem, sometimes against the concentration gradient.
ATP is required for active loading of sucrose into the sieve tubes.
The concentration of sucrose is higher in the source than in the sink.
Water moves from xylem to phloem at the source and from phloem to xylem at the sink.
Researchers manipulate a plant's phloem by selectively blocking plasmodesmata connecting companion cells to sieve tube elements near a leaf. Which outcome would provide the STRONGEST evidence AGAINST the mass flow hypothesis?
Accumulation of sucrose in the leaf and reduced transport to the roots.
Increased turgor pressure in the sieve tubes near the leaf.
Uninterrupted flow of sucrose from the leaf to the roots.
Decreased water potential in the sieve tubes near the leaf.
A researcher observes that applying a metabolic inhibitor to the sink tissues of a plant reduces the rate of translocation. How does this observation relate to the mass flow hypothesis?
It refutes the hypothesis, as metabolic energy should not be required for passive flow.
It supports the hypothesis, as reduced sink activity would decrease the pressure gradient driving flow.
It is irrelevant to the hypothesis, as the inhibitor's effect is localized to the sink.
It partially supports the hypothesis, suggesting an additional active component to the predominantly passive flow.
A researcher modifies a plant's guard cells to overexpress aquaporins. Under water-deficient conditions, which of the following is the MOST LIKELY consequence?
Increased stomatal opening
Increased transpiration
Increased water uptake
Increased stomatal closure
A scientist aims to modify the human insulin gene to increase its binding affinity to the insulin receptor. Which amino acid substitution within the insulin A-chain is MOST likely to achieve this, considering its role in receptor interaction?
A. Valine at A3 to Leucine
B. Glycine at A1 to Glutamic acid
C. Isoleucine at A2 to Valine
D. Glutamine at A5 to Asparagine
A novel enzyme is discovered that catalyzes the hydrolysis of a specific peptide bond. Kinetic studies reveal a of 10 μM and a of 50 μmol/min. A competitive inhibitor with a of 2 μM is added at a concentration of 5 μM. What will be the apparent and in the presence of the inhibitor?
Km' = 35 μM, Vmax' = 50 μmol/min
Km' = 10 μM, Vmax' = 25 μmol/min
Km' = 25 μM, Vmax' = 50 μmol/min
Km' = 35 μM, Vmax' = 25 μmol/min
The Nernst equation can be used to predict the membrane potential if a membrane is permeable to a single ion. If the external concentration of is 10 mM and the internal concentration is 100 mM at 25°C, calculate the Nernst potential for . (R = 8.314 J/mol·K, F = 96485 C/mol)
+59 mV
-59 mV
+29.5 mV
-29.5 mV
A researcher exposes two genetically identical plants to different light intensities. Plant A receives high intensity monochromatic red light, while Plant B receives low intensity polychromatic light. Assuming all other factors are optimal, which statement is MOST likely true regarding the quantum yield of photosystem II (ΦPSII)?
Plant A will likely have a higher ΦPSII than Plant B.
Plant B will likely have a higher ΦPSII than Plant A.
The ΦPSII will be approximately equal in both plants.
The ΦPSII will be zero in both plants due to the different light conditions.
Under anaerobic conditions, if a cell utilizes glucose exclusively via glycolysis, what would be the net ATP yield per glucose molecule if the glyceraldehyde-3-phosphate dehydrogenase reaction is bypassed by a hypothetical enzyme that directly converts glyceraldehyde-3-phosphate to 3-phosphoglycerate without generating NADH?
0 ATP
2 ATP
4 ATP
6 ATP
In a hypothetical scenario, a cell has a mutated form of aldolase that cleaves fructose 1,6-bisphosphate into two molecules of dihydroxyacetone phosphate. How many net ATP molecules would be produced from one molecule of glucose under anaerobic conditions in this cell?
0 ATP
2 ATP
4 ATP
6 ATP
