Year 11 Module 1: Cells as the Basis of Life

Which of the following statements is NOT a tenet of classical cell theory?

• Cells can spontaneously generate from non-living matter

• Cells are the fundamental unit of life

• All organisms are made up of one or more cells

• All cells come from pre-existing cells

Answer explanation

The statement "Cells can spontaneously generate from non-living matter" is NOT a tenet of classical cell theory. This theory asserts that all cells arise from pre-existing cells, not from non-living matter.

Which of the following is a characteristic of prokaryotic cells?

• Contain a nucleus

• Have membrane-bound organelles

• Found in animals and plants

• DNA is free-floating in the cytoplasm

Answer explanation

Prokaryotic cells lack a nucleus and membrane-bound organelles. Their DNA is not enclosed; instead, it is free-floating in the cytoplasm, distinguishing them from eukaryotic cells, which have a defined nucleus.

What is the primary function of the cell membrane?

• To provide structural support

• To control the exchange of materials in and out of the cell

• To produce energy

• To store genetic information

Answer explanation

The primary function of the cell membrane is to control the exchange of materials in and out of the cell, regulating what enters and exits, which is essential for maintaining homeostasis.

Which type of microscope uses electron beams to produce images?

• Scanning electron microscope

• Light microscope

• Fluorescence microscope

• Phase-contrast microscope

Answer explanation

The scanning electron microscope (SEM) uses electron beams to create detailed images of surfaces, unlike light microscopes which use visible light. This makes SEM ideal for observing fine structures at a microscopic level.

What is the process called when a cell engulfs solid particles?

• Pinocytosis

• Phagocytosis

• Exocytosis

• Osmosis

Answer explanation

The process when a cell engulfs solid particles is called phagocytosis. This is distinct from pinocytosis, which involves the uptake of liquids, and exocytosis, which is the expulsion of materials from the cell.

Which of the following substances can easily move through the cell membrane via passive transport?

• Glucose

• Lipids

• Water

• Proteins

Answer explanation

Water can easily move through the cell membrane via passive transport due to its small size and polarity, allowing it to pass through aquaporins. In contrast, glucose, lipids, and proteins require specific transport mechanisms.

What is the role of enzymes in cellular metabolism?

• To store energy

• To catalyse reactions by lowering the energy required

• To provide structural support

• To transport nutrients

Answer explanation

Enzymes play a crucial role in cellular metabolism by catalyzing reactions, which lowers the activation energy required for those reactions to occur. This accelerates metabolic processes essential for life.

Which of the following is NOT a type of endocytosis?

• Receptor-mediated endocytosis

• Phagocytosis

• Exocytosis

• Pinocytosis

Answer explanation

Exocytosis is NOT a type of endocytosis; it refers to the process of vesicles fusing with the plasma membrane to release contents outside the cell, while endocytosis involves the uptake of materials into the cell.

What is the main difference between autotrophs and heterotrophs?

• Autotrophs use cellular respiration, heterotrophs do not

• Autotrophs are unicellular, heterotrophs are multicellular

• Autotrophs have a nucleus, heterotrophs do not

• Autotrophs perform photosynthesis, heterotrophs consume other organisms

Answer explanation

The main difference is that autotrophs perform photosynthesis to produce their own food, while heterotrophs obtain energy by consuming other organisms. This distinction is fundamental in understanding ecological roles.

What happens to enzymes at high temperatures or extreme pH levels?

• They become more efficient

• They denature and lose their function

• They replicate faster

• They convert into different proteins

Answer explanation

At high temperatures or extreme pH levels, enzymes denature, meaning they lose their specific structure and, consequently, their function. This is why the correct answer is that they denature and lose their function.