Flashcards
BIOLOGY
Cards in this deck (15)
- 1Give two differences in structure between prokaryotic and eukaryotic cells [2 marks]Any from:
- prokaryotic cells are smaller than eukaryotic cells
- prokaryotic cells don't have mitochondria but eukaryotic cells do
- prokaryotic cells don't have a true nucleus but eukaryotic cells do
- prokaryotic cells have circular DNA but eukaryotic - 2An onion cell is viewed under a microscope with x100 magnification. the image of the cell is 7.5mm wide. what is the real width of the onion cell? give your answer in μm [2 marks]real size= image size+magnification
= 7.5mm ÷ 100
=0.075mm
0.075 x 1000 = 75μm - 3why might you add stain to the sample on a microscope slide? [1 mark]To highlight objectives within the sample by adding color to them
- 4plants transport food substances from the leaves to growing parts of the plant through phloem tubes. give one feature of a phloem cell that makes it specialized for its function. [1 mark]- They have few sub-cellular structure
- they're joined end to end
- they're long - 5describe how a root hair cell is specialized for its function [2 marks]The cell have a hair like shape, which gives it a large surface area to absorb water and minerals from the soil
- 6describe the events of the cell cycle that need to occur before mitosis can begin [2 marks]the cell has to increase the amount of its sub-cellular structures and duplicate its DNA
- 7how can stem cells be used to preserve rare plant species? [2 marks]copies of the plant can be made by talking stem cells from the meristem of the plant and growing them into new genetically of them
- 8A student dds a drop of ink to a glass of cold water. a) what will the student observe to happen to the drop of ink. explain your answer. [2 marks]the ink will spread out through the water. this is because the ink particles will move from a higher concentration of them to where it is a lower concentration of them.
- 9b) how might the observation differ if the ink was added to a glass of warm water? [1 mark]the ink particles will spread out faster
- 10Explain what will happen to the mass of a piece of potato added to a concentrated salt solution [2 marks]water will move out of the piece of potato by osmosis, so its mass will decrease
- 11what is the purpose of active transport in the gut? [1 mark]active transport allows nutrients such as glucose to move from a lower concentration in the blood
- 12a bacterial cell can be represented by a 2μm x 2μm x 1μm block. calculate the cells surface area to volume ratio. [3 marks]( 2x2) x2 =8
( 2x1) x4 =8
8x8 = 16 μm²
volume: 2x2x1 4 μm²
so the surface area to volume ratio is 16 : 4 or 4:1 - 13give one way in which alveoli are adapted for gas exchange [1 mark]E.g. they have a large surface area.
they have a moist lining for dissolving gases.
they have very thin walls.
they have a good blood supply. - 14describe how the surface area of the small intestine is maximized for absorption [1 mark]the surface of the small intestine is covered with small projections/villi
- 15give 2 ways in which the structure of a gill is adapted for effective gas exchange [2 marks]Any 2 from:
-it is made up of gill filaments which give a large surface area
-each gill filament is covered in lameilae, which further increases the surface area
-the lameliae have a thin surface area of cells
- the lameliae have lots of capillaries
- a large concentration gradient is maintained between the water and the blood