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3.2 Cells
Quick questions on Eukaryotic cell structure: organelles and their functions - AQA A-Level Biology
15short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is the cytoskeleton?Show answer
The cytoskeleton is a network of protein filaments (microfilaments, intermediate filaments and microtubules) through the cytoplasm. It gives the cell mechanical support and shape, moves organelles and vesicles, and drives chromosome movement in mitosis and the beating of cilia and flagella.
What is cell-surface membrane?Show answer
A phospholipid bilayer with proteins. Controls what enters and leaves and is the site of cell signalling and recognition.
What is nucleus?Show answer
Bounded by a double membrane (nuclear envelope) with nuclear pores. Contains chromatin (DNA plus histone proteins) and a nucleolus that makes ribosomes. Stores genetic information and controls the cell through transcription.
What is mitochondria?Show answer
Double membrane; the inner membrane is folded into cristae, surrounding a fluid matrix. Site of aerobic respiration and ATP synthesis. Cells with high energy demand (muscle, liver) have many.
What are chloroplasts?Show answer
Found in plants and algae. Double membrane plus internal thylakoid membranes stacked into grana, surrounded by stroma. Site of photosynthesis.
What are ribosomes?Show answer
Small structures of rRNA and protein, either free in the cytoplasm or attached to the endoplasmic reticulum. Site of translation (protein synthesis). Eukaryotic ribosomes are 80S; the 70S type is found in prokaryotes, mitochondria and chloroplasts.
What is rough endoplasmic reticulum?Show answer
A network of membranes studded with ribosomes. Folds and transports proteins destined for secretion or the membrane.
What is smooth endoplasmic reticulum?Show answer
Membranes without ribosomes. Synthesises and processes lipids and steroids.
What are golgi apparatus and Golgi vesicles?Show answer
Stacked flattened sacs. Modifies, sorts and packages proteins and lipids (for example glycosylation) into vesicles for secretion or for forming lysosomes.
What are lysosomes?Show answer
Golgi-derived vesicles containing hydrolytic (digestive) enzymes. Break down worn-out organelles, ingested material and, in white blood cells, engulfed pathogens.
What is cell wall?Show answer
A freely permeable layer outside the membrane. Made of cellulose in plants, chitin in fungi. Provides mechanical strength and resists turgor pressure.
What is cell vacuole?Show answer
A large fluid-filled sac in plant cells bounded by the tonoplast. Maintains turgor and stores cell sap.
What is q1?Show answer
Name three structures found in a plant cell but not an animal cell, and give the function of each. [3 marks]
What is q2?Show answer
Explain why a cell that secretes large amounts of protein has many mitochondria. [2 marks]
What is q3?Show answer
Describe the function of the cytoskeleton. [3 marks]