B1 Cell Structure Flashcards
How do you find magnification?
Magnification = Size of image / size of real object
(IAM triangle)
How do you calculate the total magnification of a microsope?
Total Magnification = Eyepiece lens x Objective lens
What is resolution?
The ability to distinguish between two separate points of an image
Define ‘Magnification’
Magnification is how much bigger an image is compared to its actual size.
This can be calculated using the IAM triangle.
What type of microscope is used to see organelles?
Electron Microscope
How do you calculate percentage change in mass?
(Final mass - Initial mass) / (initial mass)
What is a Prokaryotic Cell?
Smaller and simple cells with no nucleus
What is a Eukaryotic Cell?
A complex cell containg a nucleus
What is the function of the nucleus?
Contains genetic material (DNA) in the form of chromosomes, controls the cell
What is the cytoplasm?
This is where chemical reactions occur
What occurs in the mitochondria?
Where aerobic respiration takes place
What happens in the chloroplasts?
This where photosynthesis occurs
What happens in the ribosomes?
Where protien synthesis takes place
What is the cell membrane?
Controls what enters and leaves the cell
What is the cell wall?
A layer of cellulose used to strengthen and protect the cell
What is the vacuole?
Contains the cell sap,water and minerals
How do you get from 1000 micrometers to 1mm?
Divide by 1000
What is the equation for aerobic respiration?
Glucose + Oxygen ——> Carbon Dioxide + Water Vapour + Energy (ATP)
What type of DNA do prokaryoitc cells have?
1 single loop of DNA called plasmids
Define diffusion.
The movement of particles from a high concentration to a low concentration
Define osmosis
The movememt of water particles from a dilute solution to a concentrated solution through a partially permeable membrane
What is a passive process?
An activity which dosen’t require ATP energy
What is an active process?
An activity which ATP energy is required
What is active transport?
The diffusion of substances
What happens to an animal cell when it is placed in a more DILUTE solution?
The cell gains water by osmosis and may burst. This is called lysis.
What happens to an animal cell when it is placed in a more CONCENTRATED solution?
The cell loses water by osmosis and shrivels. This is called crenation.
What happens to a plant cell when it is placed in a more DILUTE solution?
The cell gains water by osmosis but does not burst. This cell is now turgid.
Why does a plant cell not burst when it is placed in a more dilute solution?
The plant cell has a cell wall.
What happens to an plant cell when it is placed in a more CONCENTRATED solution?
The cell loses water by osmosis. The cell membrane pulls away from the cell wall. This is is called plasmolysis.
Give an example of a substance that moves by active ranspor
Mineral ions
Adaptations of Sperm Cells
- Streamlined head and a long tail (to help swim)
- Many mitochondira to aid movement
- Contains a digestive enzyme to break the outer layer of the egg
Adaptations of nerve cells
- Nerve endings contain many mitochondria
- Long axons to enable impulses to be carried along long distances
- Has many extenstions from the cell for branced connections
Adaptations of muscle cells
- Lots of mitochondria
- Store glycogen
- Have special protiens which slide over each other (causing muscles to contract)
Adaptations of root hair cells
- Large surface area to store more water
- Large permanent vacuole (affects the speed of osmosis from soil to cell)
- Lots of mitochondria (energy needed for active ranspor)
Adaptations of xylem cells
- Hollow
- Joined end to end to form a continuous tube
- Lignin is deposited in spirals (which helps the cell wall withstand high pressure)
Adaptations of phloem cells
- Have a companion cell with mitochondria to supply energy
- Fewer organelles for food to move faster
- Cell walls form structures called sieve plates allowing the movement of substances from cell to cell
Pros and Cons of an electron microscope
Pros
- higher magnification and resolution (can see organelles)
Cons
- expensive
- can’t see colour
Pros and Cons of a light microscope
Pros
- image is coloured
- cheap
- high voltage isn’t required
cons
- limited magnification
How do you convert mm into µm
X1000
If you place a human hair on a microscope slide, and look at it under a microscope, is the hair itself considered the object or the image?
Object, The hair itself is the object because it’s the real hair sitting on the slide.
If you look at cheek cells under a microscope, are the shapes that you see when looking down the microscope the object or the image?
Image, The shapes you see are the image because they are a magnified version of the real object, created by the microscope
How do you convert µm into mm?
Divide by 1000
How do bacteria reproduce?
By binary fission,
How do you making bacteria culture with aspetic techniques?
1) Lift the lid of the petri dish towards flame to sterilse
2) Spread a drop of culture on agar evenly
3) Put discs of antibiotic on culture if needed
4) Few bits of tape (to allow aerobic respiration) and incubate at 25°C
5) Later, measure size of area with no bacteria
Why is osmosis passive?
Because it requires no energy
