What this area covers
- Cell structure and organelle function
- The four macromolecules and what each does
- DNA, RNA and protein synthesis
- Mitosis and meiosis
- Mendelian genetics and Punnett squares
- Enzymes and metabolism
Concepts that come up most in our question bank:
Where students lose marks
Mitosis and meiosis phases get confused under time pressure, especially the difference between what separates in meiosis I and meiosis II.
How to study it
For genetics, draw the Punnett square rather than doing it mentally — it takes fifteen seconds and removes most errors. For cell division, remember that meiosis I separates homologous pairs and meiosis II separates sister chromatids.
Practice questions
Answer these, then check them to see the full explanation for every option — including why each wrong answer is wrong.
- Question 1
What is the primary function of mRNA in protein synthesis?
Correct answer: B. Messenger RNA (mRNA) is transcribed from DNA in the nucleus and carries the genetic code (in the form of codons) to the ribosome in the cytoplasm, where it serves as the template for protein synthesis (translation).
- A. Carrying amino acids to the ribosome is the function of transfer RNA (tRNA), not mRNA.
- C. Ribosomal RNA (rRNA) forms the structural and catalytic components of the ribosome, not mRNA.
- D. Gene regulation involves transcription factors, enhancers, silencers, and regulatory RNA (like miRNA), not mRNA's primary function.
- Question 2
Which of the following correctly describes the process of photosynthesis?
Correct answer: A. Photosynthesis: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Plants use sunlight to convert carbon dioxide and water into glucose and oxygen in the chloroplasts.
- B. This describes cellular respiration, the reverse process. Respiration breaks down glucose using oxygen to produce CO₂, water, and ATP.
- C. This describes the Haber process for ammonia synthesis, an industrial chemical reaction, not a biological process.
- D. This partially describes anaerobic fermentation (producing ethanol), not photosynthesis.
- Question 3
Which type of cell division produces gametes (sex cells) with half the number of chromosomes?
Correct answer: B. Meiosis is a specialized cell division that produces four haploid gametes (egg or sperm cells) from one diploid parent cell. It involves two rounds of division (meiosis I and II), reducing the chromosome number by half (from 46 to 23 in humans).
- A. Mitosis produces two identical diploid daughter cells (with the full chromosome number). It is used for growth and repair, not gamete production.
- C. Binary fission is the method of cell division in prokaryotes (bacteria), not a process that produces gametes.
- D. Cytokinesis is the division of the cytoplasm that occurs after mitosis or meiosis. It is part of cell division but is not the process that reduces chromosome number.
- Question 4
Which level of protein structure is determined by the amino acid sequence?
Correct answer: A. Primary structure is the linear sequence of amino acids in a polypeptide chain, determined by the gene that encodes the protein. This sequence dictates how the protein will fold into its higher-order structures.
- B. Secondary structure refers to local folding patterns like alpha helices and beta sheets, formed by hydrogen bonds between backbone atoms.
- C. Tertiary structure is the overall 3D shape of a single polypeptide, determined by interactions between R-groups (side chains).
- D. Quaternary structure involves the arrangement of multiple polypeptide subunits into a functional protein complex (e.g., hemoglobin has 4 subunits).
- Question 5
Which of the following best describes the function of enzymes?
Correct answer: B. Enzymes are biological catalysts — they lower the activation energy of chemical reactions, dramatically increasing reaction rates without being permanently altered or consumed. Each enzyme is specific to its substrate (lock-and-key or induced-fit model).
- A. Structural support is provided by structural proteins like collagen, keratin, and actin, not by enzymes.
- C. DNA and RNA store and transmit genetic information, not enzymes.
- D. Hemoglobin transports oxygen. While hemoglobin is a protein, it is not an enzyme.
- Question 6
What is the role of the cell membrane?
Correct answer: B. The cell membrane (plasma membrane) is a selectively permeable phospholipid bilayer that controls the movement of substances into and out of the cell. It contains embedded proteins for transport, signaling, and cell recognition.
- A. Rigid structural support is provided by the cell wall (in plants, fungi, and bacteria), not the cell membrane. Animal cells lack a cell wall.
- C. Energy production occurs in the mitochondria, not the cell membrane.
- D. DNA is stored in the nucleus (in eukaryotes) or the nucleoid region (in prokaryotes), not in the cell membrane.
- Question 7
Which of the following is NOT a characteristic shared by all living organisms?
Correct answer: B. Photosynthesis is performed only by plants, algae, and some bacteria — not by all living organisms. Animals, fungi, and many bacteria cannot photosynthesize. All living organisms share characteristics including cellular organization, reproduction, response to stimuli, growth, metabolism, and homeostasis.
- A. All living organisms are composed of one or more cells — this is part of the cell theory.
- C. All living organisms respond to environmental stimuli in some way.
- D. All living organisms reproduce, either sexually or asexually.
- Question 8
A human somatic cell contains 46 chromosomes. How many chromosomes would be in a human gamete?
Correct answer: C. Gametes (sperm and egg cells) are haploid — they contain half the number of chromosomes as somatic cells. In humans: somatic cells have 46 (diploid, 2n), while gametes have 23 (haploid, n). When two gametes fuse during fertilization, the diploid number is restored.
- A. 92 would be double the somatic cell number. This is not a normal chromosome count in human cells.
- B. 46 is the diploid number found in somatic cells, not gametes.
- D. 12 is not the correct haploid number for humans.
- Question 9
Which type of bond holds the two strands of DNA together?
Correct answer: B. The two strands of the DNA double helix are held together by hydrogen bonds between complementary base pairs (A-T has 2 hydrogen bonds; C-G has 3 hydrogen bonds). These bonds are weak individually but collectively provide stability while allowing the strands to separate during replication and transcription.
- A. Ionic bonds involve the transfer of electrons between atoms. They are found in salts like NaCl, not between DNA bases.
- C. Covalent bonds connect the sugar and phosphate groups in the DNA backbone (phosphodiester bonds) but do not hold the two strands together.
- D. Peptide bonds connect amino acids in proteins, not nucleotides in DNA.
- Question 10
Which of the following is an example of a producer in a food chain?
Correct answer: D. Producers (autotrophs) are organisms that make their own food from inorganic substances using energy from sunlight (photosynthesis) or chemical reactions (chemosynthesis). Grass is a producer — it converts solar energy into chemical energy (glucose) through photosynthesis.
- A. A rabbit is a primary consumer (herbivore) that eats producers, not a producer itself.
- B. A hawk is a tertiary consumer (carnivore/predator) that eats other consumers.
- C. A mushroom is a decomposer that breaks down dead organic matter, returning nutrients to the soil.
Keep going
TEAS Dojo has 80 questions on biology alone, plus timed full-length exams across all four sections.
Start studying free →