Pre AP Biology -CELLS 1.1 Biomolecules- MCQ Exam Style Questions -New Syllabus

Pre AP Biology -CELLS 1.1 Biomolecules- MCQ Exam Style Questions – New Syllabus 2025-2026

Pre AP Biology -CELLS 1.1 Biomolecules- MCQ Exam Style Questions – Pre AP Biology – per latest Pre AP Biology Syllabus.

Pre AP Biology – MCQ Exam Style Questions- All Topics

Question

Rank the following atoms/nutrients in descending order of abundance in a plant, and for each explain why you picked it in its order.

1. nitrogen
2. sulfur
3. oxygen
4. iron
5. phosphorus

▶️ Answer/Explanation

Detailed solution

1. Oxygen ($O$): Most abundant as it is a primary component of water and organic molecules.
2. Nitrogen ($N$): A key macronutrient required for proteins, nucleic acids, and chlorophyll.
3. Phosphorus ($P$): A macronutrient essential for $ATP$, phospholipids, and DNA/RNA backbones.
4. Sulfur ($S$): A macronutrient found in specific amino acids like cysteine and methionine.
5. Iron ($Fe$): A micronutrient required only in trace amounts for electron transport and enzymes.
The descending order of abundance is: $Oxygen > Nitrogen > Phosphorus > Sulfur > Iron$.

Question

Which statement refers to chlamydias?

a. They lack peptidoglycan and are Gram-positive.

b. They lack peptidoglycan and are Gram-negative.

c. They are not pathogenic and have an outer membrane in the cell wall.

d. They are pathogenic and lack an outer membrane in the cell wall.

▶️ Answer/Explanation

Detailed solution

The correct option is b.
Chlamydias are a unique group of bacteria that are obligate intracellular parasites.
They are structurally Gram-negative, possessing both an inner and outer membrane.
However, their cell walls are unusual because they lack peptidoglycan.
Instead of peptidoglycan, they use cross-linked proteins for structural integrity.
Most species in this group are pathogenic, causing various diseases in humans.
Therefore, statement b accurately describes their physiological and staining characteristics.

Question

Many signal transduction pathways are initiated by a signal binding to a membrane receptor. Which of these statements describes this type of signalling mechanism?

a. Signal transduction first activates a protein kinase.

b. A signal molecule injected into the cytoplasm will activate the pathway.

c. Signal transduction pathways never include components within the nucleus.

d. A mutation in a single gene can disrupt an entire signalling pathway.

▶️ Answer/Explanation

Detailed solution

The correct option is d.
Signalling pathways consist of a series of interconnected molecular interactions.
A mutation in a single gene can result in a dysfunctional protein or enzyme.
Because these components act in a relay, one broken link can halt the entire downstream signal.
Option a is incorrect because pathways often begin with receptor conformational changes or $G$ protein activation.
Option b is incorrect because membrane receptors require extracellular binding, not cytoplasmic injection.
Option c is incorrect as many pathways eventually target transcription factors within the nucleus.

Pre AP Biology -CELLS 1.1 Biomolecules- MCQ Exam Style Questions -New Syllabus