Biology 11–12 Standard Challenge

Question 1

In DNA replication, which enzyme joins Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Answer

Helicase

Answer

Primase

Answer

DNA polymerase I

Question 2

Which phase of meiosis is most directly responsible for independent assortment of chromosomes?

Accepted Answer

Metaphase I

Answer

Prophase I

Answer

Anaphase II

Answer

Telophase I

Question 3

A plant cell placed in a strongly hypertonic solution will most likely show which immediate response?

Accepted Answer

The plasma membrane pulls away from the cell wall

Answer

The cell wall dissolves

Answer

The vacuole expands and turgor increases

Answer

Chloroplasts stop containing chlorophyll

Question 4

During aerobic respiration, most ATP in eukaryotic cells is generated during which process?

Accepted Answer

Oxidative phosphorylation

Answer

Glycolysis

Answer

Krebs cycle

Answer

Fermentation

Question 5

Which blood vessel carries oxygenated blood from the lungs to the heart?

Accepted Answer

Pulmonary vein

Answer

Pulmonary artery

Answer

Aorta

Answer

Superior vena cava

Question 6

In a food web, what is the most likely consequence of removing a top predator from a stable ecosystem?

Accepted Answer

Prey populations may increase sharply

Answer

Primary producers immediately disappear

Answer

Decomposers stop recycling nutrients

Answer

Energy flow reverses direction

Question 7

Which part of the neuron is primarily responsible for receiving incoming signals from other neurons?

Accepted Answer

Dendrite

Answer

Axon terminal

Answer

Myelin sheath

Answer

Node of Ranvier

Question 8

A cross between two heterozygous pea plants for seed shape (Rr × Rr) produces what expected genotypic ratio?

Accepted Answer

1 RR : 2 Rr : 1 rr

Answer

3 RR : 1 rr

Answer

2 RR : 1 Rr : 1 rr

Answer

1 RR : 1 Rr : 2 rr

Question 9

Which hormone is primarily responsible for lowering blood glucose levels in humans?

Accepted Answer

Insulin

Answer

Glucagon

Answer

Adrenaline

Answer

Thyroxine

Question 10

Which statement best explains why enzymes can become ineffective at very high temperatures?

Accepted Answer

Their active sites change shape due to denaturation

Answer

They are converted into lipids

Answer

They permanently increase substrate concentration

Answer

They stop colliding with molecules entirely

Biology 11–12 Standard Challenge

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