B1 Cell Structure And Transport Flashcards
Diffusion
The net movement of particles from an area of high concentration to an area of low concentration.
Why does diffusion happen?
Due to the random movement of the particles, they bounce into each other and obstacles.
How much energy is used in diffusion?
It is a passive process which means no energy is needed.
Concentration gradient
The difference in concentration between two areas.
Steep concentration gradient
Faster diffusion
Shallow concentration gradient
Slower diffusion.
Higher temperature
Faster diffusion as particles have more energy.
Lower temperature
Slower diffusion.
Large surface area
Faster diffusion.
Small surface area
Slower diffusion.
Osmosis
The movement of water from a dilute solution to a more concentrated solution.
Partially permeable membrane
Membranes that only let some particles through them.
Isotonic
Same
Hypertonic
Higher
Hypotonic
Lower
Magnification =
Size of image / size of real object
Resolution
The ability to distinguish between two seperate points
Nucleus
Controls all the activities of the cell. Contains the genes on the chromosomes that carry the instructions for making the proteins needed to build new cells or new organisms
Cytoplasm
A liquid gel in which the organelle are suspended and where most of the chemical reactions needed for life take place
Cell membrane
Controls the passage of substances such as glucose and mineral ions into the cell. Also controls the movement of substances such as urea or hormones out of the cell
Mitochondria
Structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell
Ribosomes
Where protein synthesis takes place, making all the proteins needed in the cell
Cell wall
Strengthens the cell and gives it support. Made of cellulose
Chloroplasts
Contain the green substance chlorophyll which absorbs light so the plant can make food by photosynthesis
Permanent vacuole
A space in the cytoplasm filled with cell sap. Keeps the cell rigid and helps to support the plant
Eukaryotic cells
Cells that have a membrane, cytoplasm, and genetic material enclosed within a nucleus
Prokaryotic cells
Cells which do not have a nucleus- the DNA is free in the cytoplasm
Plasmids
Small rings of DNA found in some prokaryotic cells, which code for very specific features such as antibiotic resistance
Flagella
Long protein strands that lash out and allow the bacteria to move
Adaptations of nerve cells
Lots of dendrites to make connections to other nerve cells, an axon that carries the nerve impulse from one place to another, and the nerve endings are adapted to pass impulses using special transmitter chemicals (they contain lots of mitochondria to provide the energy needed to make the chemicals)
Adaptations of striated muscle cells
Special proteins that slide of each other making the fibres contract, many mitochondria to transfer the energy needed for the chemical reactions that take place as the cells contract and relax, and they can contain glycogen (a chemical that can be broken down and used in cellular respiration by the mitochondria to transfer the energy needed for the fibres to contract)
Adaptation of sperm cells
A long tail whips from side to side to help it move, the middle section is full of mitochondria which transfer the energy needed for the tail to work, the acrosome stores the digestive enzymes for breaking down the outer layers of the egg, and a large nucleus contains the genetic material to be passed on
Adaptations of root hair cells
They greatly increase the surface area available for water to move into the cell, large permanent vacuole that speeds up movement of water by osmosis from the soil across the root hair cell, many mitochondria transfer the energy needed for the active transport of mineral ions into the cell
Adaptations of photosynthetic cells
Chloroplasts contain chlorophyll, which traps the light needed for photosynthesis, usually positioned in the leaves and outer layers of the stem of a plant so they absorb more light, and have a large permanent vacuole which keeps the cells rigid as a result of osmosis
Adaptations of xylem cells
Xylem cells are alive when first formed but the chemical lignin builds up in spirals in the cell walls and the cells die to form long hollow tubes, and the spirals or lignin make them very strong and help withstand the pressure of the water moving up
Adaptations of phloem cells
Cells walls break down to form special sieve plates which allow water carrying dissolved food to move freely up and down. Phloem cells are supported by their companion cells that help keep them alive. The mitochondria of the companion cells transfer the energy needed
Diffusion occurs down a…
Concentration gradient
Plasmolysis
When too much water is lost from osmosis, the vacuole and cytoplasm shrink, and eventually the cell membrane pulls away from the cell wall
Flaccid
Soft
Turgid
Normal
