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45 Cards in this Set
- Front
- Back
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All cells have...
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Nucleus Mitochrondia Cell Membrane Ribosomes Cytoplasm |
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Plant cells have...
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Cell Wall Chloroplasts Vacuole |
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Milimetre to micrometer
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x1,000
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Micrometre to nanometer
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x1,000
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Millimetre to nanometer
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x1,000,000
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Total magnification
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Eyepiece magnification x objective magnification
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Actual size formula
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Real size = Size of image / Magnification
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Length of Cell (nanometre) formula
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Length = No: of cells in image / 1,000
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What is a Eukaryotic Cell?
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Animal and Plant cells
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What is a Prokaryotic Cell?
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Single Cell Organisms
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What do Prokaryotic Cells have Eukaryotic Cells don't?
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Slime Capsule (occasionally) Plasmids Loose Genetic Material Flagella (occasionally) |
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What do Eukaryotic Cells have Prokaryotic Cells don't?
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Nucli
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What is differentiation? |
Differentiation is the process where a cell changes to become specialised |
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When can differentiation happen in plants and animals? |
In plants it can happen anytime. The meristem tissue differentiates In animals it can only occur when an organism develops |
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What are the 6 examples of specialised cells? |
Sperm cells Nerve cells Muscle cells Root hair cells Phloem cells Xylem cells |
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How are sperm cells specialised? |
Sperm cells are specialised for reproduction. Long tail and streamlined head to help it swim A lot of mitochondria to provide energy Carries a lot of enzymes to digest the egg cell membrane |
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How are nerve cells specialised? |
Nerve cells are specialised for rapid signalling Nerve cells need to carry electrical signals in the body Long to cover more distance Branched connections to their ends connect to create a network |
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How are nerve cells specialised? |
Nerve cells are specialised for rapid signalling Nerve cells need to carry electrical signals in the body Long to cover more distance Branched connections to their ends connect to create a network |
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How are muscle cells specialised? |
Muscle cells are specialised for contraction Muscles cells need to contract quickly Long so they have space to contract Lots of mitochondria for energy |
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How are root hair cells specialised? |
Root hair cells are specialised for absorbing water and minerals Hairs to give them a large surface area for absorbing water and mineral ions from the soil |
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How are phloem cells specialised? |
Phloem cells are specialised for transporting food Long and joined end to end to form tubes Small pores to allow cell sap to flow Few subcellular structures so stuff can flow |
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How are xylem cells specialised? |
Xylem cells are specialised for transporting water Long and joined end to end to form tubes Hollow in the centre |
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What are chromosomes? |
Genetic material found in the nucleus Coiled up DNA molecules |
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What are chromosomes? |
Genetic material found in the nucleus Coiled up DNA molecules |
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How many pairs of chromosomes are there in a human cell? |
23 |
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What are chromosomes? |
Genetic material found in the nucleus Coiled up DNA molecules |
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How many pairs of chromosomes are there in a human cell? |
23 |
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Why are chromosomes in pairs? |
There are two copies of each chromosome, one from each parent |
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What does the cell cycle do? |
The cell cycle makes new cells for growth, development and repair |
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What takes places in the cell cycle? |
1) DNA is spread out into long strings 2) Has to grow and increase the amount of subcellular structures e.g. mitochondria and ribosomes 3) It then exactly duplicates its DNA. It formed X-shaped chromosomes
Mitosis starts
4) The chromosomes line up and the cell fibres split them. Two arms go to opposite ends of a cell 5) Membranes form around each set of chromosomes (this becomes the nuclei). The nucleus has divided 6) The cytoplasm and cell membrane divide
Two new daughter cells are formed containing the same DNA. Identical to the parent cells |
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What takes places in the cell cycle? |
1) DNA is spread out into long strings 2) Has to grow and increase the amount of subcellular structures e.g. mitochondria and ribosomes 3) It then exactly duplicates its DNA. It formed X-shaped chromosomes
Mitosis starts
4) The chromosomes line up and the cell fibres split them. Two arms go to opposite ends of a cell 5) Membranes form around each set of chromosomes (this becomes the nuclei). The nucleus has divided 6) The cytoplasm and cell membrane divide
Two new daughter cells are formed containing the same DNA. Identical to the parent cells |
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Explain binary fission |
1) Binary fission takes place in prokaryotic cells 2) Circular DNA and plasmids replicate 3) The cell enlarges and the circular DNA moves to opposite ends of the cell 4) The cytoplasm begins to divide and a new cell wall starts to 5) The cytoplasm divides and two new daughter cells are produced. 6) Each has one copy of circular DNA but variable numbers of plasmids |
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A bacterial cell had a mean division time of 30 minutes. How many cells will it have produced after 2.5 hours? |
(2.5 hours)/(30 minutes) 2.5 hours x 60 = 150 minutes (150 minutes)/(30 minutes) = 5 divisions 2^5=32 32 cells |
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What is a stem cell? |
An undifferentiated cell |
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Why are stem cells medically useful? |
Replace faulty blood cells Create insulin-productive cells for diabetes Replace nerve cells for people paralysed by spinal injuries Therapeutic cloning can be used to make sure the transplant isn't rejected |
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Why are people against stem cells? |
Stem cells could become contaminated in a lab Potential human life |
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What is diffusion? |
Diffusion is the spreading out of particles from an area of high concentration to an area of lower concentration |
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How does diffusion happen in cells? |
It happens in cell membranes They hold the cell together and let stuff in and out Only lets some glucose, amino acids, water and oxygen Doesn't let in protein or starch because they're too big |
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What is osmosis? |
Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration |
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How does gas exchange happen in the lungs? |
1) Lungs transfer oxygen to the blood and remove carbon dioxide 2) Gas exchange occurs in the alveoli 3) Alveoli are adapted to maximise diffusion - Large surface area - Moist lining - Thin walls - Good blood supply |
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How does the small intestine maximise diffusion and active transport? |
1) Covered in villi 2) Increase surface area 3) Digested food is absorbed quicker - Single layer of surface cells - Good blood supply |
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What is active transport? |
Active transport is used when the concentration gradient goes the opposite way as necessary. Root hair cells and the gut |
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How do single-celled organisms use diffusion? |
Gases and dissolved substance can diffuse directly into or out of the cell membrane
This is because they have a large surface area compared to their volume |
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How do leaves use diffusion? |
The water vapour evaporated inside the cells in leaves. It then escapes by diffusion because there's a large amount inside the leaf and not a lot in the air outside
1) Carbon dioxide diffuses into air spaces within the leaf which then diffuses into cells. Photosynthesis then happens 2) Oxygen and water vapour then diffuse out of the stomata 3) The size of the stomata are controlled by guard cells |
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How do gills do gas exchange? |
1) Water enters the fish through its mouth and passes out through its gills. Oxygen diffuses into the blood and carbon dioxide diffuses out of the blood into the water 2) Gills have - Gill filaments for a large surface area - Lots of blood capillaries - Blood and water flows in opposite directions. This maintains a concentration gradient |
