B1 Flashcards
What are the 2 types of focus on a microscope?
Coarse and Fine
What is the lens of a light microscope called?
Objective lens
How many m are in a km
1000
How many cm are in a m
100
How many mm are in a cm
10
How many mm’s are in a micrometer
1000
How many micrometers are in a nanometre
1000
How far can a light microscope measure up to?
X2000
What resolving power does a light microscope have?
200nm
How much can an electron microscope measure?
X2000000
What is the resolving power of a electron microscope
0.2nm
What is the magnification equation?
Magnification= Size of image divided by size of object
What is the function of the nucleus?
Controll all cell activities, contains genes on the chromosomes that carry instructions for making protiens
What is the function of the cytoplasm?
A liguid gel where organelles are suspended and where most of the chemical reactions needed for life occur
What is the function of the cell membrane?
Controls the passage of substances such as glucose and mineral ions into the cell and urea and hormones out of the cell
What is the function of the mitochondria
Structures in the cytoplasm where aerobic respiration takes place
What if the function of ribosomes?
Where protein synthesis takes place, making all the proteins needed in a cell
What are chloroplasts?
A substance that absorbs light so the plant can carry out photosynthesis
Why are chloroplast Green?
As they contain chlorophyll?
Why don’t root cells contain chloroplast?
As they are underground and don’t carry out photosynthesis
What is a permanent vacuole?
A space in the cytoplasm filled with cell sap, this keeps the cells rigid to support the plant
What are the main structures of an animal cell?
A nucleus, cytoplasm, cell membrane, mitochondria and ribosomes
What are 3 extra features of a plant cell that animal cells don’t contain?
Chloroplast, a cell wall and a permanent vacuole
What are 2 examples of eukaryotic and cells?
Plant and animal cells
What do eukaryotic cells contain?
Cell membrane, cytoplasm and genetic material that is enclosed in a nucleus
What makes up a prokaryotic cell?
Cytoplasm and a cell membrane sorrounded by a cell wall
What is 2 differences between prokaryotic and eukaryotic cells?
Prokaryotic cells’ DNA is free but a eukaryotic cells’ DNA is in a nucleus
Prokaryotic cells have no organelles,only ribosomes but eukaryotic cells have membrane-bound organelles
What does a prokaryotic cell have that a eukaryotic cell does not?
A flagella
What does eukaryotic cells have that prokaryotic cells don’t?
A nucleus
What is an example of a prokaryotic cell?
Bacteria
What are the 3 types of specialised animal cells?
Nerve cell
Muscle cell
Sperm cell
How are nerve cells specialised and how do they make their cell more effective?
-Lots of dendrites to make connections to other nerve cells
-an axon that carries the nerve impulse from one place to another
-the nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body
How are muscles cells specialised?
-They contain special proteins that slide over each other making the fibres contract
-Contain many mitochondria to transfer the energy needed for chemical reactions to take place
-Store glycogen( a chemical that can be broken down and used in cellular respiration)
How are sperm cells specialised?
-A long tail to help move through water or the female reproductive system
- The middle section is full of mitochondria which transfer the r Getty needed for the tail to work
-The across one stores digestive enzymes for breaking down the outer layers of the egg
- A large nucleus that contains genetic information
What are examples of specialised plant cells?
Root hair cells
Photosynthetic cells
Xylem cells
Phloem cells
How are root hair cells specialised?
-Increase surface are available for water to move into the cell
-large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell
- Mitochondria that transfer energy needed for active transport
How are photosynthetic cells specialised?
-Contain chloroplasts containing chlorophyll that trap sunlight for photosynthesis
- Positioned in continuous layers in the leaves and outer layers of the stem of a plant so they absorb more light
-large permanent vacuole that helps keel the cell rigid
How are xylem cells specialised?
-Lignin builds up on spirals in the cell wall and when the cell dies long hollow tubes that allow water and mineral ions to move through them form
-Spirals and rings of lignin in the xylem cells make them very strong to help withstand pressure of water moving up the plant
How are phloem cells specialised?
-Cell wall between the cells break down to form special sieve plates
-Supported by companion cells that keep them alive
What is diffusion?
The movements of particles from an area of high concentration to an area of low concentration
What affects the rate of diffusion?
Difference in concentration, temperature and available surface area
What substances and gasses use diffusion to move in and out of cells?
Glucose, urea and oxygen and carbon dioxide
What is osmosis?
Movement of water molecules from an area of high concentration to an area of low concentration across a partially permeable membrane
What causes water to move into or out of the cell by osmosis?
Concentrations of solutions inside and outside a cell
What happens if the concentration outisde the cell changes dramatically?
Animal cells can be damaged
What causes the solution to be isotonic to the cell?
The concentration of solutes in the solution outside the cell is the same as the internal concentration
What causes the solution to be hypertonic to the cell?
The concentration of solutes in the solution outside the cell is higher than the internal concentration
What causes the solution to be hypotonic to the cell?
The concentration of the solutes outside the cell is lower than the internal concentration
Why is osmosis important in plant cells?
As it helps to maintain turgor in plant cells
What are the 6 steps of looking at cells(REQUIRED PRACTICAL)?
- Move the stage down to the lowest position
- Place the glass slide onto the stage
3.select the lowest power objective lens
4.turn the coarse focus slowly untill you are able to see the cells
5.Turn the fine focus untill the cells are in focus - Repeats steps 1-5 using higher power magnification
What happens when water moves out and in a planet cell by osmosis
The plant shrinks and expands
What are the steps of osmosis?
1.Peel potato
2.Use a cork borer to produce 3 cylinders of potato
3.Use a scalpel to trim cylinders to 3cm in length
4.Meausre length of cylinder using ruler and the mass using a balance
5.Put each cylinder into a test tube, add 10cm cubes of a 0.5 molar sugar solution to the first tube
6.Then add 10cm cubed of 0.25 molar sugar solution to the second test tube and 10cm cubed of distilled water to the last tube
7.Leave solutions over night
8. Remove potato cylinders and gently roll them on a paper towel to remove surface moisture
9. Don’t press on them
10. Measure length and mass of cylinders
11. Calculate percentage change
Why do we use a cork borer instead of a knife?
As each potato will be the same size
What is active transport?
The moving of substances from a more dilute solution to a more concentrated solution against a concentration gradient
How does active transport get the energy required to carry out active transport?
Uses energy released from food in respiration to provide the energy required
What does active transport allow root hairs to do?
Absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentration gradient
What does active transport allow sugar molecules to do?
To be absorbed from lower concentrations in the gut into the blood where the concentration of sugar is higher
What do single-called organisms have?
A large surface area to volume ratio so all necessary exchanges with the environment take place over this surface
In multicellular organisms, what are the organs specialised with?
Effective exchange surfaces
