1.1 Cell Structure & Function (Cambridge (CIE) O Level Biology): Flashcards
Exam code: 5090
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- FrontAnimal & Plant Cells
Define the nucleus.
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Cards in this collection (36)
Define the nucleus.
A cell structure that contains the genetic material (DNA), which controls the activities of the cell.
Define mitochondria.
The site of aerobic respiration, where energy is released for the cell. Large numbers are found in very active cells, such as muscle cells.
Define ribosomes.
Tiny structures that are the site of protein synthesis; found free in the cytoplasm or attached to the endoplasmic reticulum.
Define the permanent vacuole.
A fluid-filled sac in plant cells containing cell sap (a solution of sugars and ions); used for storage and to support the cell.
What is the function of the cytoplasm?
A gel-like substance made of water and dissolved solutes that supports the internal cell structures and is the site of many chemical reactions.
State three structures found in a plant cell that are not found in an animal cell.
Cellulose cell wall
Chloroplasts
A large permanent vacuole containing cell sap
Name two structures that are only visible at higher magnification using an electron microscope.
Ribosomes
Rough endoplasmic reticulum (RER)
Vesicles are also only visible at this higher magnification.
Give three conventions that should be followed when making a biological drawing of cells.
Use a sharp HB pencil with clear, single lines and no shading
Include a title and the magnification
Draw label lines with a ruler, not crossing and without arrowheads
Chloroplasts contain the green pigment , which absorbs light energy for photosynthesis.
Chloroplasts contain the green pigment chlorophyll, which absorbs light energy for photosynthesis.
The controls which substances enter and leave the cell.
The cell membrane controls which substances enter and leave the cell.
True or False?
Animal cells store carbohydrate as glycogen, whereas plant cells store it as starch.
True.
Animal cells store carbohydrate as glycogen; plant cells store it as starch (or sucrose).
True or False?
Plant cells are able to move from place to place.
False.
Animals can move from place to place; plants cannot, and plants also lack nervous coordination.
Why must a very thin sample be used when viewing cells under a light microscope?
Light has to pass through the sample and into the lenses to produce a visible image.
Define a stain.
A coloured chemical added to a specimen to make cell structures clearly visible under the microscope.
Cheek cells are commonly stained with before viewing under a light microscope.
Cheek cells are commonly stained with methylene blue before viewing under a light microscope.
Onion epidermis cells are commonly stained with before viewing under a light microscope.
Onion epidermis cells are commonly stained with iodine before viewing under a light microscope.
Why should you always start with the lowest power objective lens?
It is easier to find the specimen in the field of view
It helps prevent damage to the lens or coverslip
Name four parts of a cell that can be seen with a light microscope.
Nucleus
Mitochondria
Cell membrane
Cytoplasm
Why is onion epidermis an ideal plant tissue to view under the microscope?
It forms a layer just one cell thick, so light passes through easily. It is also not green, as it contains no chloroplasts.
What type of cells are collected when scraping the inside of the cheek?
Squamous epithelial cells from the outer epithelial layer of the mouth.
Why is a drop of water added to a specimen beneath the coverslip?
To prevent the thin layer of cells from drying out (dehydration) and being damaged.
A coverslip should be lowered at first and then tilted flat to reduce air bubbles.
A coverslip should be lowered at one edge first and then tilted flat to reduce air bubbles.
True or False?
Cheek cells should be sampled from someone who has a cold or throat infection.
False.
Avoid sampling from someone with a cold, cough or throat infection to prevent spreading infection to others.
True or False?
Ribosomes can be seen clearly using a light microscope.
False.
Ribosomes are too small to be seen with a light microscope; only larger structures such as the nucleus, mitochondria, cell membrane and cytoplasm are visible.
Define bacteria.
Microscopic single-celled organisms that lack a nucleus (prokaryotes).
Define a plasmid.
A small ring of DNA in bacteria, separate from the main chromosome, that carries extra genes.
Name four structures found in a bacterial cell.
Cell wall
Cell membrane
Cytoplasm
Ribosomes
A circular chromosome of DNA is also present.
Instead of a nucleus, a bacterial cell contains a circular of DNA floating in the cytoplasm.
Instead of a nucleus, a bacterial cell contains a circular chromosome of DNA floating in the cytoplasm.
A bacterial cell wall is made of , not cellulose.
A bacterial cell wall is made of peptidoglycan, not cellulose.
What is the function of a flagellum in a bacterial cell?
A long, thin, whip-like tail that allows the bacterium to move.
How does a bacterial cell differ from an animal cell in the way it stores its DNA?
Bacterial DNA is a circular chromosome free in the cytoplasm (plus plasmids), whereas animal DNA is enclosed within a nucleus.
Give one example of a useful bacterium and state what it is used for.
Lactobacillus — a rod-shaped bacterium used to make yoghurt from milk.
Give one example of a bacterium that causes disease.
Pneumococcus — a spherical bacterium that causes pneumonia.
True or False?
Bacteria contain mitochondria and chloroplasts.
False.
Bacteria lack mitochondria, chloroplasts and other membrane-bound organelles.
True or False?
Plasmids contain the same genes as the main bacterial chromosome.
False.
Plasmids carry extra genes to those found in the chromosomal DNA.
Define a flagellum.
A long, thin, whip-like tail attached to some bacteria that allows them to move.
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