Aiming for a Grade 4
Controls all the activities of the cell
Nucleus
The net movement of water from an area of high concentration (of water) to an area of low concentration (of water)
Osmosis
List the 5 parts of an animal cell
1 Cell membrane
2 Mitochondria
3 Cytoplasm
4 Nucleus
5 Ribosomes
Give the formula for calculating magnification
magnification = size of image / size of real object
tiny air sacs in the lungs that increase the surface area for gaseous exchange
alveoli
Controls what goes in and out of the cell.
Cell membrane
The net movement of particles of a gas or solute from an area of high concentration to an area of low concentration.
Diffusion
List the 8 parts of an animal cell
Cell wall
Cell membrane
Cytoplasm
Mitochondria
chloroplasts
Nucleus
Ribosomes
Vacuole
Red blood cells and onion cells do not contain all the sub-cellular components normally present in a typical plant or animal cell.
Name the sub-cellular structure normally found in animal cells that is missing in a red blood cell.
Nucleus
a solution that is more concentrated than the cell contents
hypertonic (osmosis)
Filled with cell sap. Keeps the cell rigid to support the plant.
Vacuole
The movement of substances against a concentration gradient/or across a cell membrane, using energy.
Active transport
Give the function of each cell part:
Cell wall
Cell membrane
Cytoplasm
Mitochondria
chloroplasts
Nucleus
Ribosomes
Vacuole
Cell membrane Controls what goes in and out of the cell.
Chloroplast Absorbs light energy to make food by photosynthesis.
Cell Wall Made of cellulose, strengthens the cell and gives it support.
Vacuole Filled with cell sap. Keeps the cell rigid to support the plant.
Cytoplasm A liquid gel in which most of the chemical reactions needed for life take place.
Nucleus Controls all the activities of the cell.
Mitochondria Release energy during respiration.
Ribosomes Where protein synthesis takes place.
Red blood cells and onion cells do not contain all the sub-cellular components normally present in a typical plant or animal cell.
Explain how this adaptation benefits the cell.
Increases surface area of cell to enable it to carry more oxygen.
a solution that is less concentrated than the cell contents
hypotonic (osmosis)
Absorbs light energy to make food by photosynthesis.
Chloroplast
Which of these substances can diffuse across cell membranes?
Carbon dioxide; oxygen; water; sugars
all four
explain the function and special features of these specialised cells:
Root hair cell
Fat cell
Cone cell
Xylem cells
Root hair cell Absorbs water from the ground Has a projection which gives it a large surface area to collect water
Fat cell Stores fat as an energy supply Small amount of cytoplasm and a large amount of fat. Few mitochondria
Cone cell Detect colour Contain a pigment that changes chemically in coloured light. Has a specialised synapse that connects to optic nerve
Xylem cells Transport of water throughout the plant Spirals of lignin withstand the pressure of water mo
Name sub-cellular structure normally found in plant cells that is missing in an onion cell and explain why this structure is not needed by an onion cell.
Chloroplasts.
Onion bulb is underground/idea of no light reaching cell, so does not photosynthesise.
openings in the leaves of plants, particularly on the underside and opened and closed by guard cells, allowing gases to enter and leave the leaf
stomata
A liquid gel in which most of the chemical reactions needed for life take place.
Cytoplasm
Choose the right word for each bracketed section to show your understanding of exchanging materials in living organisms.
As living organisms get bigger, their surface area to volume ratio gets (smaller / larger). This makes it increasingly difficult to exchange materials quickly enough with the outside world so in many (larger / smaller) organisms there are special surfaces where the exchange of materials takes place. These surfaces are adapted to be as effective as possible by:
• having a (large / small) surface area that provides a big / small area over which exchange can take place
• having a (thin / thick) membrane or being thin to provide a short diffusion path
• having an efficient blood supply that moves the diffusing substances away from the exchange surfaces and (maintains / lowers) the concentration gradient.
• Keeping the area of gas exchange well ventilated, which makes gas exchange (more / less) efficient by maintaining steep concentration gradients.
smaller, larger, large, big, thin, maintains, more
Describe each of these three processes:
Diffusion
Osmosis
Active transport
Active transport: The movement of substances against a concentration gradient/or across a cell membrane, using energy.
Diffusion: The net movement of particles of a gas or solute from an area of high concentration to an area of low concentration.
Osmosis: The net movement of water from an area of high concentration (of water) to an area of low concentration (of water).
A student measured the diameter of a human capillary on a micrograph. The capillary image measures 5 mm across, and the student knows the image magnification is x1000.
Using the formula:magnification = observed cell length / actual cell length
calculate the diameter of the capillary in mm and then give your answer in micrometres
0.005 mm
5 µm
the state of plant cells when so much water is lost from the cell by osmosis that the vacuole and cytoplasm shrink and the cell membrane pulls away from the cell wall
plasmolysis