Cell Structure and Microscopes Flashcards
How do you calculate the total magnification of a microscope?
Eyepiece lens magnification x objective lens magnification
How do you calculate the magnification of an image?
Size of image ÷ real size of object
How many micrometres are in a millimetre?
1,000 (one thousand)
How many nanometres are in a millimetre?
1,000,000 (one million)
What is 120 000 000 in standard form?
1.2 × 10^8
What is 0.000007 in standard form?
7 × 10^-6
How can you improve the resolution of a microscope (make it clearer)?
Turn the fine focus knob
How can you improve the magnification of an image when using a microscope (make it bigger)?
Turn to a higher power objective lens
Who first observed cork cells using a compound microscope?
Robert Hooke
What is a limitation of the light microscope?
Fairly low resolution - cannot distinguish 2 points closer than 200 nm.
Which cell structure is only visible when using an electron microscope (and not with a light microscope)?
Ribosomes
What is the function (job) of the cytoplasm?
A jelly-like material where most chemical reactions happen
What is the function (job) of the nucleus?
Contains genetic material (e.g. DNA), and controls the cell’s activities
What is the function (job) of the cell membrane?
Controls the movement of substances into and out of the cell
What is the function (job) of the mitochondria?
The site of aerobic respiration, which releases energy to the cell
What is the function (job) of the ribosomes?
The site of protein synthesis (where proteins are made)
Which three organelles (structures) are found in a plant cell, but not in an animal cell?
Chloroplasts, vacuole, cell wall
What is the function (job) of the chloroplasts?
The site of photosynthesis, a chemical reaction where plants make their own food
What is the function (job) of the cell wall?
Strengthens the cell and supports the plant
What is the name of the green pigment in the chloroplasts that absorbs sunlight for photosynthesis?
Chlorophyll
What is the cell wall made from?
Cellulose fibres
What is the vacuole filled with?
Cell sap
What is the function (job) of the vacuole?
Helps to keep the plant cell turgid
How many orders of magnitude bigger is a 700 μm cell than a 7 μm cell?
2 orders of magnitude (10^2)
What are three examples of eukaryotic cells?
Animals, plants and fungi
What is an example of a prokaryotic cell?
Bacteria
What are three structures NOT found in a bacterial (prokaryotic) cell?
- Nucleus
- Mitochondria
- Chloroplasts
How is DNA stored in a bacterial cell?
- Free in the cytoplasm
- Additional DNA is stored in rings called plasmids
How do bacterial cells divide?
By binary fission
Name three adaptations a sperm cell has to help it perform its function.
- The acrosome (head) contains enzymes so the sperm can penetrate the egg
- The middle piece contains many mitochondria to release the energy needed for the sperm to swim
- The tail enables the sperm to swim
- The sperm has a streamlined shape
Name three adaptations a nerve cell has to help it perform its function (job).
- Nerve cells are extended to help them run to and from different parts of the body
- Nerve cells have extensions and branches to help them communicate with other nerve cells
- The nerve cell is covered with a fatty sheath, which insulates the cell and speeds up the electrical impulse
What is one way that muscle cells are adapted for their function (job)?
Muscle cells contain many mitochondria to release the energy needed for muscle contraction
What are two adaptations of a root hair cell to allow it to carry out its function (job)?
- Large surface area for absorbing more water
- Thin cell walls - not to restrict movement of water
How are xylem cells adapted for their function (job)?
- No top and bottom walls between xylem cells, so water can flow freely
- Thickened woody walls to support the plant
What is the function of the xylem vessel in plants?
To carry water
What is the function of the phloem vessel in plants?
To carry dissolved sugars and amino acids
