Flashcards in B1 - Cell Biology Deck (45):
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotic are single celled (bacteria)
Eukaryotic are more complex cells (animals and plants)
What do plant cells have that animal cells don’t?
What does the cell membrane do?
Controls what goes in and out of cells.
What happens in the cytoplasm?
What do ribosomes make?
What does the nucleus do?
Contains genetic info and controls what goes in and out the cell.
What happens in mitochondria?
Aerobic respiration takes place.
What does the cell wall do?
It supports the plant cell.
What happens in chloroplasts?
What does a vacuole contain and control?
Contains cell sap to control the water and keep the cell turgid.
What do prokaryotic cells contain?
Strands of DNA
Small rings of DNA called plasmids.
What is the difference between light and electron microscopes?
Light microscopes use lights and lenses but electron microscopes use electrons and have a higher magnification.
What is the equation to work out magnification?
Magnification = image size/real size
What does one mm equal in micrometers?
What is differentiation?
The process where cells change to become specialised for a job/to carry out specific functions.
When does most differentiation occur?
When an organism develops or needs cells to be repaired/replaced.
What are undifferentiated cells?
How are sperm cells specialised?
Specialised for reproduction - have streamlined tails and a pointed head.
How are nerve cells specialised?
Specialised of rapid signalling - branched connections.
How are muscle cells specialised?
Specialised for contraction - have mitochondria for energy.
How are root hair cells specialised?
Specialised for absorbing water and minerals - large SA and small hairs.
How are phloem and xylem tubes specialised?
Specialised for transporting food and water - allow stuff to flow through/hollow centre.
What does the cell cycle do?
Makes new cells for growth, development and repair.
What are the events that take place before mitosis can start?
-Cell has to grow and increase amount of mitochondria/ribosomes.
-It duplicates DNA so it has one copy for each new cell (this forms into x shaped chromosomes)
What happens in mitosis?
-Chromosomes line up in the centre of the cell and cell fibres pull them apart.
-Membranes form around each two sets of chromosomes and nucleus divides.
-Cytoplasm and cell membrane divides producing two new daughter cells.
What are undifferentiated cells and what do they do?
Have potential to turn into any kind of cell at all.
Where can stem cells be found and what do they help with?
Bone Marrow - Can replace faulty blood cells
Embryos - produce insulin producing cells, nerve cells, can be cloned to help parents be treated.
Why are some people against stem cells?
People can think it’s taking away potential human life.
Why are some people for stem cells?
Life of the living is more important than the unborn.
Embryos used would often be thrown away/unwanted.
What to stem cells on plants do?
Found in the meristems - can produce clones of rare species or others very quickly.
What is diffusion?
The spreading out of particles from an area of high concentration to low.
In diffusion; the higher the concentration gradient ...
The faster the rate of reaction.
Where do cells use diffusion?
Through the cell membrane:
Dissolved substances (oxygen, water, amino acids) move in and out of a cell through diffusion.
What is osmosis?
The movement of water molecules across a partially permeable membrane from a high concentration to low.
What is a partially permeable membrane?
One with very small holes in it - only water can pass through.
What does the overall net movement mean?
Water is travelling in both directions but the overall net movement is which direction its travelling in to dilute a solution.
What is active transport?
The movement of substances which are going against a concentration gradient.
How does active transport happen in root hair cells?
When there are more minerals in the cell than in the soil, active transport is used to help the absorb minerals. It requires a lot of energy.
How does active transport happen in humans?
In the gut. There is usually more nutrients in the blood then the gut so active transport allows nutrients to be absorbed in the blood and used for respiration.
How do you work out volume and surface area of an organism?
Volume = length x width x height
SA = length x width
How have multicellular organism adapted for better diffusion?
-Thin membranes: less to travel through
-Large SA: more diffusion
-in animals: blood vessels and ventilation
How are the lungs adapted for good gas exchange?
They contain lots of little air sacs (alveoli) which help the exchange of O2 and CO2. They have:
-Good blood supply
How is the small intestine adapted for good absorption of food?
Contains lots of villis which have:
-Single later of cells
-Good blood supply
How are leaves adapted for exchanging surfaces?
The leaf cell contains stomata on the underneath of the plant which allows CO2, O2 and H2O to diffuse in and out.
These stomata are controlled by guard cells that close if the plant is losing to much water.