Free IB Biology Questions and Answers

Question 1

A DNA mutation known as a ___________ alters the DNA sequence but does not modify the amino acids in a protein.

Accepted Answer

Silent mutation

Answer

A silent mutation is a type of point mutation where a change in a single DNA nucleotide base occurs, but this change does not alter the amino acid sequence of the protein produced. This is possible because the genetic code is degenerate, meaning multiple codons can code for the same amino acid. Therefore, even with a DNA sequence change, the resulting protein remains functionally identical.

Question 2

In an experiment, helminthes infection was given to mice, and population shifts were tracked. It was discovered that as mice got worse, their numbers fell. This connection is an illustration of ________.

Accepted Answer

Parasitism

Answer

Parasitism is a symbiotic relationship where one organism, the parasite (in this case, helminthes), benefits at the expense of the other organism, the host (the mice). The observation that the mice's condition worsened and their numbers fell due to the infection clearly indicates that the helminthes are harming the mice, which is the defining characteristic of a parasitic relationship.

Question 3

The existence of ________ in plant cells sets them apart from animal ones.

Accepted Answer

Cell wall

Answer

Plant cells are uniquely characterized by the presence of a rigid cell wall, primarily composed of cellulose, located outside the cell membrane. This structure provides essential support, protection, and helps maintain cell shape. Animal cells, in contrast, lack a cell wall, relying solely on their cell membrane for their outermost boundary.

Question 4

Which two different types of chemicals are involved in translation?

Accepted Answer

mRNA and protein

Answer

Translation is the biological process where the genetic information encoded in messenger RNA (mRNA) is used to synthesize proteins. During this process, ribosomes read the mRNA sequence, and transfer RNA (tRNA) molecules bring specific amino acids, which are then linked together to form a polypeptide chain, ultimately creating a protein. Thus, mRNA provides the template, and proteins are the final product.

Question 5

Which of the following is not a part of the endocrine system?

Accepted Answer

Testis

Answer

The endocrine system comprises glands that secrete hormones directly into the bloodstream to regulate various bodily functions. While the heart and liver have some endocrine functions (e.g., producing ANP and IGF-1, respectively), and the testis is a major endocrine gland producing testosterone, the lung's primary role is gas exchange. Although it has some metabolic functions, it is not typically classified as a primary endocrine gland in the same manner as the testis.

IB - International Baccalaureate Practice Test

IB - International Baccalaureate Practice Test

Free IB Biology Questions and Answers