Chapter 1 - Cell Structure And Transport Flashcards
What forms the image in a typical school microscope?
A beam of light.
The length of an onion cell in an image is 12mm. The magnification is X570. What is the size of the real cell?
Length of cell = 12mm = 12 000μm
real size = 12 000/570
= 21μm.
In which part of the cell is energy transferred during respiration?
Mitochondria.
What is the function of chloroplasts?
To absorb light for photosynthesis.
Onion cells do not look green. Explain why.
Onion bulb cells do not contain chloroplasts for photosynthesis because they are underground and do not receive light.
Where is the DNA found in a prokaryotic cell?
In the cytoplasm as a long circle of DNA, and in plasmids.
What is the order of magnitude of 1cm compared with 1mm?
1 order of magnitude (or 10^1).
Muscle cells contain a lot of mitochondria. Why?
Mitochondria transfer energy during aerobic respiration; muscle cells need energy to contract.
Which organ system contains nerve cells?
The nervous system.
What is the main function of the root hair cell?
To take up water and mineral ions from the soil.
Name the chemical that makes xylem rigid.
Lignin.
What determines the net movement of particles across a cell membrane?
The concentrations of the particles on either side of the membrane.
Describe what is meant by gas exchange in the lungs.
The diffusion of oxygen and carbon dioxide in opposite directions.
What type of membrane is the cell membrane?
Partially permeable.
What term is used to refer to two solutions with identical concentrations?
Isotonic.
When does turgor pressure occur in a plant cell?
When water enters the cell by osmosis, causing the vacuole to swell, which presses the cytoplasm against the cell wall.
If potato chips are placed in pure water, will they get bigger or smaller? Explain your answer.
Bigger. Because water moves into the potato cells by osmosis.
Why does active transport require energy?
The particles are being absorbed against a concentration gradient.
Name a substance that is moved by active transport into plants from the soil solution.
Mineral ions (or a named mineral)
Why do large organisms need specialised exchange surfaces?
Large organisms have a small surface area to volume ratio; exchange surfaces allows materials to be passed to a transport system, which carries them to all the cells.
How are leaves adapted to increase their surface area?
Leaves are flat and thin, and have internal air spaces and stomata.
Calculate the surface area : volume ratio of a cube with sides 2cm long
24:8 or 3:1
