IB Biology 5

Question 1

Which gas exchange organ allows insects to obtain oxygen without a circulatory system carrying it to cells?

Accepted Answer

Tracheae

Answer

Insects have a tracheal system — a network of air tubes (tracheae) that deliver oxygen directly to tissues, bypassing the need for blood to transport it.

Question 2

What is the significance of the semi-conservative replication model demonstrated by Meselson and Stahl?

Accepted Answer

Each new DNA molecule retains one original strand and one newly synthesized strand

Answer

The Meselson-Stahl experiment showed that after one round of replication each daughter double helix contains one parental strand and one newly made strand.

Question 3

Which type of immunity involves memory B and T cells that respond rapidly upon re-exposure to an antigen?

Accepted Answer

Active acquired immunity

Answer

Active acquired immunity results from exposure to an antigen (through infection or vaccination) and creates immunological memory for faster secondary responses.

Question 4

What is a keystone species?

Accepted Answer

A species that has a disproportionately large effect on community structure relative to its abundance

Answer

A keystone species exerts an outsized influence on its ecosystem, often through predation or habitat modification, and its removal causes dramatic community changes.

Question 5

What is the product of translation?

Accepted Answer

A polypeptide chain assembled from amino acids

Answer

Translation is the process by which ribosomes read mRNA codons and assemble a corresponding sequence of amino acids into a polypeptide.

IB - International Baccalaureate Practice Test

IB - International Baccalaureate Practice Test

IB Biology 5