B1 - Cell Structure and transport Flashcards
How does a light microscope work?
Light microscopes use a beam of light to form an image
How does an electron microscope work?
Electron microscopes use a beam of electrons to form an image
Give a pro and con of light microscopes:
Pro
Relatively cheap
Can be used almost anywhere
Can produce colour images
Small - takes up less room
Con
Low resolving power
Give a pro and con of electron microscopes:
Pro
Higher resolution
Higher magnification
Can see tiny sub-cellular structures
Con
Very expensive
Must be kept in certain conditions
Large - take up a lot of space
Only produces black and white images
What are the two types of eukaryotic cell?
Animal and plant
What type of cell are bacteria?
Prokaryotic
Where is DNA found in animal and plant cells?
Nucleus
What is the function of the cell membrane?
Controls movement of substances in and out of the cell
What is the function of mitochondria?
Site of aerobic cellular respiration to transfer energy for the cell
What is the function of chloroplasts?
The organelles in which photosynthesis takes place. Contains chlorophyll to absorb light energy for photosynthesis
What is the function of ribosomes?
Where protein synthesis takes place, making all the proteins needed in the cell
What is the function of the cell wall?
Made of cellulose
Strengthens and supports the cell
What is the structure of the main genetic material in a prokaryotic cell?
Single loop of DNA
What is the function of a red blood cell?
Carries oxygen around the body
Give 2 adaptations of a red blood cell:
No nucleus
Contains a red pigment called haemoglobin
Has a bi-concave disc shape
What is the function of a nerve cell?
Carries electrical impulses around the body
Give 2 adaptations of a nerve cell:
Branched endings
Myelin sheath insulates the axon
What is the function of a sperm cell?
Fertilises an ovum (egg)
Give 2 adaptations of a sperm cell:
Long tail whips from side to side to help move sperm to egg
Middle section has mitochondria to transfer energy needed for tail to work
Acrosome stores digestive enzymes for breaking down outer layers of egg
Large nucleus contains genetic information to be passed on
What is the function of a muscle cell?
Specialised cell that contracts and relaxes in pairs to move the skeleton/ move food through gut
Give 2 adaptations of muscle cells:
Contains special proteins that slide over each other making the fibres contract
Contains mitochondria to transfer energy needed for the chemical reactions that take place as the cells contract and relax
Can store 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
What is the function of a palisade cell?
Carries out photosynthesis in a leaf
Give 2 adaptations of a palisade cell:
Lots of chloroplasts
Located at the top surface of the leaf
What is the function of a root hair cell?
Absorbs minerals and water from the soil
Give 2 adaptations of a root hair cell?
Long projection - surface area
Lots of mitochondria to transfer energy needed for active transport
What is osmosis?
A special case of diffusion. The movement of water from a dilute to a more concentrated solution through a partially permeable membrane.
What is active transport?
The movement of substances from an area of low concentration to an area of high concentration. It goes against a concentration gradient, requiring energy from respiration.
What is a partially permeable membrane?
A membrane that only allows certain substances to pass through
What is passive transport?
The movement of substances from an area of high concentration to an area of low concentration, requiring no energy.
Moves down concentration gradient.
What is diffusion?
The spreading out of particles of any substance in a solution, or particles in a gas, resulting in a net movement of particles from an area of high to low concentration down a concentration gradient.
The net movement of particles from an area of high concentration to an area of low concentration.
What is the difference between an animal and plant cell?
Animal cells don’t have a cell wall.
Animal cells don’t have chloroplasts
What is the difference between the genetic material in a prokaryotic cell and the genetic material in a eukaryotic cell?
In prokaryotic cells, the genetic material is not enclosed in a nucleus. The bacterial chromosome is a single loop of DNA found free in the cytoplasm.
Prokaryotic cells may also contain extra small rings of DNA called plasmids.
What do plasmids do?
Plasmids code for very specific features such as antibiotic resistance.
Some types of bacterium have flagella. What is this?
A long protein strand that lashes about. These bacteria use their flagella to move themselves around.
What is the nucleus?
An organelle containing genetic information and controls all the activities of the cell.
What is cytoplasm?
The water-based gel in which the organelles in all living cells are suspended and most of the chemical reactions of life take place.
What is a vacuole?
Contains cell sap (fluid) surrounded by a single membrane.
Why should you start with the lowest magnification?
Makes it easier to find what you’re looking for.
What is the equation for magnification?
Magnification = size of image/ size of real object
What is xylem?
The transport tissue in plants that carries water and mineral ions from the roots to leaves.
How has xylem adapted?
Lignin - strength
Dead - long hollow tubes
What is phloem?
The transport tissue that carries the food made by photosynthesis around the body of the plant.
What is transpiration?
The loss of water vapour from the leaves of plants through the stomata when they’re opened to allow gas exchange for photosynthesis.
What is translocation?
The movement of sugars from the leaves to the rest of the plant through the phloem.
What is the rate of diffusion affected by?
Concentration difference
Temperature
Surface area
Isotonic = ?
Hypertonic = ?
Hypotonic = ?
Isotonic = equal
Hypertonic = higher outside
Hypotonic = lower outside
