B1 Flashcards
1 kilometre is how many metres ?
1000
1 metre is how many centimetres ?
100
1 cm is how many millimetres ?
10
1 mm is how many micrometres ?
1000
1 micrometre is how many nanometres ?
1000
How does a light microscope work ?
They use a beam of light to form an image of an object .
What can a light microscope magnify up to ?
2000 times
What has the electron microscope allowed us to do ?
We are now able to see and understand more about subcellular structures inside cells .
How does an electron microscope work ?
a beam of electrons are used to form an image and can magnify up to 2,000,000 times
What are three disadvantages of the electron microscope ?
- They are very expensive
- They have to be kept at a specific temperature
- They are large
If you are given an image of inside a cell , how do you calculate the magnification ?
magnification = size of image/size of real object
What is the other equation of magnification ?
eyepiece lens x objective lens
What is the objective lens ?
Used to magnify an image at different magnification levels
What is the eyepiece lens ?
The lens you look through
What is the definition of resolution ?
The ability to distinguish between two seperate points
What are the main sub cellular structures in animal cell ?
Nucleas , cyctoplasm , cell membrane , ribosomes and mitochondria
What is the function of the nucleas ?
controls everything that happens in the cell . Contains chromosomes which hold genes and DNA strands .
What is the function of cyctoplasm ?
This is where all the chemical reactions take place which are needed for everyday life .
What is the function of the cell membrane ?
This controls everything that comes in and out of the cell .
What is the function of mitochondria ?
This is where aerobic respiration takes place , releasing energy for the cell .
What is the function of a ribosome ?
This is where all the protein is made .
What is algae ?
A simple aquatic organism . They make their own food by photosynthesis .
What sub cellular structures does a plant cell contain ?
Nucleas , cell membrane , mitochondria , cyctoplasm , ribosomes , chloroplast , permanent vacuole and cell wall .
What are the three extra sub cellular structures that a plant cell has ?
Chloroplast , permanent vacuole and cell wall
What is chloroplast ?
contains chlorphyll which absorbs sunlight for the plant
What is the permanent vacuole ?
A space in the cyctoplasm filled with cell sap . This is important for keeping the cells rigid to the support the plant .
What are examples of eukaryotic cells ?
Animal , plant cells , fungi and prostita
Is bacteria a single celled organism ?
yes
What is an example of a prokaryotic cell ?
Bacteria
What are four differences from a eukaryotic and prokaryotic cell ?
- E - DNA is enclosed in a nucleas . whereas in P the DNA is spread out .
- Cell wall in P does not contain cellulose , whereas in a plant cell it would .
- P contain extra small DNA rings called plasmids .
- Bacteria has flagellum at the back of their cell .
What is a specialised cell ?
A cell that is specialised for a specific function .
Does a plant cell differentiate at an early stage of development ?
No they can differentiate throughout their life .
How are nerve cells specialised ?
To carry out electrical impulses around the body . They provide a rapid communication system between different parts of the body .
What three things makes a nerve cell specialised ?
- Lots of Dendrites which carry out electrical impulses around the body .
- An axon that carries the nerve impulse from one place to another .
- The synapses are adapted to pass the impul;se to another cell or btween a nerve cell and muscle in the body .
How are muscle cells specialised ?
They contract and relax
What three adaptations make a muscle cell specialised ?
- They contain special proteins that slide over each other making the fibres contract .
- They contain many mitochondria
- They can store glycegon
What is the function of a sperm cell ?
To fertilise an egg
What three things make a sperm cell specialised ?
- a long tail
- The middle section is full with mitochondria
- a large nucleas containing genetic information
What are the three main specialised cells in animal cells ?
Nerve , muscle and sperm cells .
What is the function of a root hair cell ?
The root hair cells help their plants to take up water and mineral ions more efficiently .
What three things make a root hair cell specialised ?
- They greatly increase the surface area available for water to move into the cell .
- They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil .
- They have many mitochondria that transfer energy needed for active transport .
What are three things that make a photosynthetic cell specialised ?
- Contain structures like chloroplast which contains chloropyll .
- They are usually placed in the leaf at the top so they can absorb as much sunlight as they can .
- They have a large permanent vacuole that keeps the cell rigid .
What is a xylem cell ?
A transport tissue in plants that carries water and mineral ions from the roots to the highest leaves and shoots . it is also important in supporting the plant .
What are two ways in which xylem cells are adapted ?
- The cells are dead , they form long hollow tubes that allow the water and mineral ions to move easily .
- They contain a special chemical called lignin which builds up in spirals along the cell walls . This makes the plant strong .
What is a phloem cell ?
A specialised transport tissue that carries food made by photosynthesis around the body of the plant .
What are two adaptations of the phloem cell ?
- They have sieve plates that allow water carrying dissolved foods to move freely up and down the tubes to where it is needed .
- The cells are supported by companion cells that help them to keep them alive . The mitochondria of the companion cells transfer the energy needed to move dissolved foods up and down the phloem .
Why do we need diffusion ?
Your cells need to take in substances such as glucose and oxygen for respiration . To get rid of waste and to allow dissolved substances to move into and out of your body .
What is diffusion ?
Diffusion is the spreading out of particles of a gas or of any substance in a solution .
What is net movement ?
overall movement of particles
In diffusion what is the net movement of particles ?
from an area of high concentration to low concentration .
What are two gases that can enter cells by diffusion ?
Oxygen and carbon dioxide
What four things are affected by diffusion ?
Surface area
Temprature
Concentration gradient
Diffusion distance
What is the equation for net movement ?
Particles moving in - particles moving out
How does the small intestine increase its surface area ?
The small intestine folds itself which allows more particles to move through .
What is gas exchange ?
The diffusion of oxygen and carbon dioxide in opposite directions in the lungs
What is the most common adaptation to cells to increase the surface area ?
By folding up the membrane of the cell
What is osmosis ?
This is the movement of water molecules only, from an area of high water concentration to an area of low water concentration across a partially permeable membrane .
What is a partially permeable membrane ?
A membrane that lets some molecules through but not others .
What is water potential ?
Water potential is also known as water concentration .
What is a dilute solution ?
When the solute ( the substance that is dissolved ) is lower than the solvent ( like water )
What is the experiment used for osmosis ?
The potato experiment
What is the independent variable in the potato experiment ?
The solute concentration , sugar
What is the dependent variable in the potato experiment ?
The change in mass of potato cylinders
What are the two control variables in the potato experiment ?
Temperature and surface area of potato
What is the method used for the potato experiment?
- Use a cork borer to cut 5 potato cylinders of the same diameter
- Use a scalpel and ruler to trim each potato cylinder so they are all the same length
- Measure the mass of each potato cylinder and record in a table of results
- Measure 10cm cubed of each sugar or salt solution and pour into each boiling tube
- Place the potato cylinders into each boiling tubes
- Time how long the potato cylinders are in the tube for .
- Remove the potatoes, blot dry and record the final mass
In the osmosis experiment what does a decrease in mass tell us ?
That the net movement of osmosis is out of the cell
What does the term isotonic mean in an animal cell in terms of osmosis ?
The amount of water inside and outside the is the same
What does the term hypertonic mean in terms of osmosis ?
This means that the movement of osmosis is out of the cell to a lower concentration of solution . It will become shrivelled
What does hypotonic mean in terms of osmosis ?
When water moves into the cell by osmosis it might burst
Why do plants rely on osmosis ?
To support their stems and leaves
What does turgid mean ?
When the balance of water in and out of the cell is normal
What does flaccid mean in a plant cell ?
When water moves out of the cyctoplasm
What is active transport ?
Active transport allows cells to move substances from an area of low concentration to an area of high concentration . This movement is against the concentration gradient .
Where does active transport happen in plants ?
Happens in the root hair cells from the soil to the surrounding roots
Where can active transport be seen in an animal cell ?
In the small intestine
What is needed for active transport to work ?
A lot of energy
How is the energy produced for active transport ?
Respiration
Does the ratio of surface area to volume ratio fall as objects get bigger ?
Yes
In a small object what is the surface area to volume ratio like ?
Larger surface area to volume ratio which means that their is a better exchange
In a large object what is the surface area to volume ratio like ?
Harder to exchange materials
The effectivness of an exchange surface can be increased by three things :
. Having a large surface area over which exchange can take place
. Having a thin membrane or being thin to provide a short diffusion path
. Having an efficient blood supply
What is an example of an adaptation of exchanging materials ? How are they adapted ?
Alveoli , have an enormous surface area and a very rich blood supply , for effective gas exchange
How are the villi adapted ?
They provide a large surface area and a rich blood supply
What is cystic fibrosis ?
Thick , sticky mucus in peoples lungs , gut and reproductive systems
How are fish adapted to exchange oxygen and carbon dioxide ?
Their gills
