B1 - Cell Structure and Transport Flashcards
What is the function of a cell wall?
The outer layer of a plant cell which strengthens and supports the cell
What is the function of the nucleus?
Control centre of the cell and contains all the DNA
What is the function of the cell membrane?
Controls what enters and leaves the cells
What is the function of ribosomes?
The site of protein synthesis
What is the function of the mitochondria?
The site of aerobic respiration (release of energy from food)
What is the function of the Chloroplasts?
Contains chlorophyll, site of photosynthesis
What is the function of the large permanent vacuole?
It stores cell sap
In which type of cell would you find a cell wall?
Plant cell only
In which type of cell would you find ribsomes?
Both animal and plant cells
Name 3 differences between plant cells and animal cells
Plant cells have a cell wall, a vacuole and chloroplasts whereas an animal cell does not.
How do you calculate the total magnification using a microscope?
Total magnification = Eyepiece lens x objective lens
Define resolution
the ability of a microscope to distinguish how clear the details are of a specimen
Define magnification
how much bigger an image is made, compared to it’s actual size.
What microscope do you use for viewing small organelles like ribosomes?
An electron microscope
What type of DNA do prokaryotic cells have?
circular chromosomes which is NOT enclosed by a nucleus
What type of DNA do eukaryotic cells have?
Lots of linear (straight) chromosomes which are enclosed by a nucleus
How do you calculate the magnification when using size?
. Size of image
Magnification = ————————
Real size of
Object
Give two advantages of using an electron microscope instead of a light microscope
It has higher magnification
It has higher resolution
What are examples of Eukaryotic cells?
Animal cells
Plant cells
What is an example of a prokaryotic cell?
Bacteria cells
What are the three factors that affect the rate of diffusion?
The concentration gradient
Temperature
Surface area
What does it mean if a cell membrane is partially permable?
Only some particles can diffuse through them
Why does the temperature affect the rate of diffusion?
Higher temperatures gives the particles more energy and make them move faster
Why does the surface area of the membrane affect the rate of diffusion?
A larger surface area would be a higher rate of diffusion
as there is more area for the particles to pass
What is Diffusion?
The net movement of particles from an area of higher concentration, to an area of lower concentration
What does net movement mean?
The Overall movement
How does the concentration gradeint affect the rate of diffusion?
the larger the concentration gradient (a bigger difference in particles), the faster the rate of diffusion will be
What is Osmosis
The net movement of water molecules across a partially permable membrane from a region of higher water concentration to a region of lower water concentration
What are solutes?
Dissolved particles like sugar or salt
What is Osmosis in terms of Diffusion?
It is The Diffusion of Water Molecules
What is active transport?
The movement of molecules across a mebrane, from a region of low concentration, to a region of high concentration that requires energy from cellular respiration
what does active transport need to move?
Energy from respiration
Which process provides the energy required for active transport?
Respiration
Where do plants absorb mineral ions from?
The soil
What does chlorophyll do in the chlorplasts?
Absorb light so plants can make food by photosynthesis
Why do root hair cells not need chloroplasts?
They are underground so they dont photosynthesise
Do all plants have chlorophyll?
No
What does a eukaryotic cell’s stucture include?
A cell membrane, cytoplasm and genetic material enclosed in a nucleus
What does a prokaryotic cell’s stucture include?
A cytoplasm and a cell membrane surrounded by a cell wall
Circular chromosomes not enclosed by a nucleus
How are sperm cells adapted for their function?
Streamlined head and long flagella to aid with swimming
Carries digetive enzymes in its head to digest the egg cell membrane
How are nerve cells adapted for their function?
The axon is long which means the impulses can be carried along long distances
Branched connections to make a network in the body
How are muscle cells adapted for their function?
Long and have lots of mitochondria to provide energy for contraction
How are root hair cells adapted for their function?
Have a large surface area so more water can be absorbed by osmosis
Lots of mitochondria
How are xylem cells adapted for their function?
joined end-to-end to form a hollow continuous tube so water and mineral ions can move through
How are phloem cells adapted for their function?
Have few organelles so food can move faster
What is the function of sperm cells?
To fertilise the egg cell for reproduction
What is the function of nerve cells?
Transmits electrical impulses
What is the function of muscle cells?
For movement by contraction/relaxation
Generating heat
What is the function of xylem cells in a plant?
To transport water and mineral ions from the roots to the shoots in a plant
What are plasmids?
Circles of DNA that contain non-essential genes
What is the nucleus structure of a bacterial cell?
No nucleus, only a single circulated, strand of DNA in cytoplasm
Why is diffusion decribed as a ‘passive process’?
It doesnt require any energy from the cell
Why is active transport decribed as an ‘active process’?
It requires energy from the cell
Why do root hair cells have lots of mitchondria?
To absorb mineral ions by active transport
Using a diagram, why do bacterial cells not contain mitochondria?
Bacterial cells are about the same size as a mitochondrion - no room
What are Eukaryotes made up of?
Eukaryotic cells
What are Prokaryotes made up of?
Prokaryotic cells
What is the cell wall made out of?
Cellulose
What is cell sap?
A weak solution of sugar and salts
What do light microscopes help us see?
Individual cells
Large subcellular structures (like nuclei)
How do convert from micrometers to millimetres?
Divide by 1000
How do you convert from miilmetres to micrometres?
Multiply by 1000
What is a slide in microscopy?
A clear strip of glass which the specimen is mounted on
How do prepare a slide to view onion cells in microscopy?
Add drop of water to the slide
Use tweezers to peel epidermal tissue of the onion
Place that onto the slide and add a drop of iodine solution
Place a cover slip on top.
Why do you add iodine solution to the epidermal layer of an onion when doing a microscopy practical?
Iodine solution is a stain
Stains highlight objects in a cell by giving them colour
How do you use a light microscope in microscopy?
- Clip the prepared slide onto the stage
- Select the lowest-powered objective lens and use the adjustment knob to move the stage up
- Look down eyepiece and use the adjustment knob until image is roughly in focus
- Use fine adjustment knob until image is clear
- Toggle magnification power if needed
Why dont you bring the stage all the way up when doing a microscopy experiment?
You dont want to touch the objective lens
What will happen to the mass of a potato that is added to a concentrated salt solution?
Water will move out the potato by osmosis, meaning the mass will decrease
What is the purpose of active transport in the blood?
Transporting nutrients into the blood stream even when the blood has a higher concentration
When a red blood cell and a plant cell are put into a beaker, the red blood cell bursts while the plant cell does not. Why is this?
Water enters the cells by osmosis
Thry both will swell
Plant cell wont burst as it has a cell wall
Plant cells use osmosis to absorb _______
Plant cells use acrive transport to absorb __________
Water
Mineral ions
Suggest why a student couldnt see any cells when looking through a microscope
The objective lens was dirty
The chromosomes contain the genetic material.
Name the chemical which the genetic material is made from.
DNA
A student put a thick layer of cells onto a sample
Explain why the student was unable to observe the cells with a microscope?
The light couldn’t pass through
