Cell Biology Flashcards
What are the organelles in a plant cell?
Cell wall, cell membrane, ribosomes, mitochondria, chloroplasts, cytoplasm, nucleus, vacuole
What are the organelles in an animal cell?
Cell membrane, ribosomes, mitochondria, cytoplasm, nucleus
What are the differences between eukaryotic and prokaryotic cells?
Eukaryotic cells have a nucleus and are multicellular and prokaryotic cells have a circular strand of DNA and are unicellular
What is the definition of magnification?
The aparent enlargement of an object
What is the definition of resolution?
The fineness of detail that can be seen in an image
What is the calculation for magnification?
Image = magnification x actual size
Advantages and disadvantages of light microscopes
Advantages
- cheap
- easy to use
- can magnify living cells or small organisms
Disadvantages
- requires a stain
- can’t see very small organelles
Advantages and disadvantages of electron microscopes
Advantages
- allows the observation of smaller organelles
Disadvantages
- can’t observe living organisms
- very expensive
What is a stem cell?
An undifferentiated cell that can multiply into other undifferentiated cells or differentiate into many other specialised cells
What are the two kinds of human stem cell?
Embryonic (from embryos) and adult (from certain places like bone marrow)
Which can differentiate into more kinds of specialised cells - embryonic or adult?
Embryonic
What is therapeutic cloning?
The process where an embryo can be made to have the same genetic information as the patient so the stem cell won’t be rejected
Where are stem cells found in plants?
The meristem (the roots and shoots of the plant)
What are the uses of stem cells in plants?
- Rare species of plant can be cloned to prevent extinction
- Crop plants with special features (e.g. resistance to disease) can be cloned
What is diffusion?
The net movement of particles from an area of high to low concentration down a concentration gradient
What is osmosis?
The diffusion of water; the net movement of water molecules from an area of high to low concentration down a concentration gradient through partially permeable membrane
What are the factors that affect the rate of diffusion?
Temperature - increased temperature increases the rate of diffusion
Concentration gradient - a steeper gradient increases the rate of diffusion
Surface area - increased surface area increases the rate of diffusion
What is an isotonic solution?
Any solution that has the same water concentration as the cells
What is a hypertonic solution?
A solution with a low water concentration; a cell placed in the solution will lose water by osmosis and shrink (a flaccid cell)
What is a hypotonic solution?
A solution with a high water concentration; a cell placed in the solution will have water move into it by osmosis, causing the cell to eventually burst (a turgid cell)
What are the differences between xylem and phloem cells?
Xylem is made of dead tissue and transports water and minerals (transpiration) one way through the plant - roots to shoots
Phloem is made of living tissue and transports glucose (translocation) in both directions around the plant
What is active transport?
The opposite of diffusion; moving from an area of low to high concentration against a concentration gradient
What does the rate of active transport depend on?
The rate of respiration
When is active transport used in plants?
When the concentration of minerals in the soil is lower than inside the plant, active transport is used to absorb the minerals against the concentration gradient
How are sperm cells adapted to their function?
Long tail that makes it easier to swim; they are also streamlined which makes it easier to swim
Have lots of mitochondria which provide the energy needed for swimming
Contain enzymes that allow them to fertilise the egg easier by digesting the outer layer
How are muscle cells adapted for their function?
Contain protein fibres that change their length for contractions
Have lots of mitochondria to provide energy for contractions
