Cell Structure
Aperçu
Everything a living thing does, it does with cells. A cheek cell, an oak leaf cell and a bacterium sitting on a door handle are all built from the same short list of parts, arranged differently and used for different jobs. Learn that list properly and a great deal of the rest of biology stops being memory work and starts being reasoning.
In this lesson you will name the parts of animal, plant and bacterial cells and say what each one does. You will meet the one distinction that matters most, between cells that keep their genes inside a nucleus and cells that do not, and you will practise the skill the examiners really want: looking at an unfamiliar cell, spotting what it has too much of, and working out what it must be for. The specimen Paper 1 opened on exactly this topic and spent ten marks on it, so it is worth the time.
Objectifs
- Most animal cells (eukaryotic cells) have the following parts: a nucleus, which controls the activities of the cell; cytoplasm, in which most of the chemical reactions take place; a cell membrane, which controls the passage of substances into and out of the cell; mitochondria, which is where most energy is released in respiration; ribosomes, which is where protein synthesis occurs.
- In addition to the above, plant cells (eukaryotic cells) often have: chloroplasts, which absorb light energy to make food; a permanent vacuole filled with cell sap. Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell.
- A bacterial cell (prokaryotic cell) consists of cytoplasm and a membrane surrounded by a cell wall; the genes are not in a distinct nucleus; some of the genes are located in circular structures called plasmids.
- Cells may be specialised to carry out a particular function. Students should be able, when provided with appropriate information, to relate the structure of different types of cell to their function in a tissue, an organ, or the whole organism.
Carte mentale
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Note de cours
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Cell Structure. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à lépreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- Which part of a cell controls the passage of substances into and out of it? A. The nucleus B. The cell wall C. The cell membrane D. The cytoplasm Answer: C
- Which structure is found in a plant cell but NOT in an animal cell? A. Ribosome B. Chloroplast C. Mitochondrion D. Cell membrane Answer: B
- Which two structures are found in an animal cell and also in a bacterial cell? A. Nucleus and chloroplast B. Cytoplasm and cell membrane C. Permanent vacuole and cell wall D. Nucleus and plasmid Answer: B
- Which statement about a bacterial cell is correct? A. Its genes are held in a distinct nucleus B. It contains chloroplasts C. Some of its genes are in circular plasmids D. It has no cell wall Answer: C
- A cell contains a very large number of mitochondria. What does this suggest? A. It makes a lot of protein B. It releases a lot of energy by respiration C. It photosynthesises rapidly D. It stores a lot of water Answer: B
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