IB Biology HL Paper 1 Practice Questions

Enhance your understanding of IB Biology HL with these targeted practice questions. Covering Biotechnology, Neurobiology, and Ecology, each question is paired with a detailed solution to help clarify complex concepts.

Dive in to test and strengthen your biology knowledge!

Practice Questions

1. Question 1:

   • Topic: Biotechnology

   • Question: Which enzyme is used to seal the strands of DNA together in recombinant DNA technology?

     • A) DNA polymerase

     • B) Restriction enzyme

     • C) DNA ligase

     • D) RNA polymerase

2. Question 2:

   • Topic: Neurobiology

   • Question: During the propagation of a nerve impulse, the movement of which ion is primarily responsible for depolarization of the neuron's membrane?

     • A) Sodium (Na+)

     • B) Potassium (K+)

     • C) Calcium (Ca2+)

     • D) Chloride (Cl-)

3. Question 3:

   • Topic: Ecology and Conservation

   • Question: Which of the following best describes a keystone species?

     • A) A species with the highest biomass in an ecosystem

     • B) A species that dominates in terms of population numbers

     • C) A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system

     • D) A species introduced to an ecosystem where it is not native

Worked Solutions

1. Solution to Question 1:

   • DNA polymerase is involved in the replication of DNA.

   • Restriction enzymes cut DNA at specific sequences.

   • DNA ligase is the enzyme that seals the strands of DNA together, especially in recombinant DNA technology.

   • RNA polymerase is involved in the synthesis of RNA from a DNA template.

   • Answer: C) DNA ligase

2. Solution to Question 2:

   • During depolarization of a neuron's membrane, sodium ions (Na+) flow into the neuron.

   • Potassium ions (K+) are primarily involved in repolarization.

   • Calcium ions (Ca2+) and chloride ions (Cl-) are not primarily responsible for depolarization.

   • Answer: A) Sodium (Na+)

3. Solution to Question 3:

   • A keystone species is not necessarily the one with the highest biomass or the one that is most abundant in terms of population.

   • Introduced species are not inherently keystone species.

   • A keystone species is one whose presence and role in an ecosystem have a disproportionate effect on other organisms within the system.

   • Answer: C) A species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system