B1 Flashcards
What is a eukaryotic cell?
A eukaryote is any organism whose cells have a nucleus enclosed within membranes, unlike Prokaryotes
What is a prokaryotic cell?
A prokaryote is a unicellular organism that lacks a membrane-bound nucleus, mitochondria, or any other membrane-bound organell
Give an example of a eukaryotic cell
- Animal Cells
- Fungus
- Plant cells
Give an example of a prokaryotic cell
- Bacteria
- Yeast
Give the magnification equation
Magnification=Measured size / actual size
Name things inside a plant cell
-Mitochondria
-Vacuole
-Chloroplasts
-Cytoplasm
-Ribosomes
-Cell wall
-Cell membrane
-
Name things inside an animal cell
- Flagellum
- Nucleus
- Cytoplasm
- Ribosomes
- Rough Endoplasmic Reticulum
Name things in a bacteria cell
- Capsule
- Plasmid
- Pili
- Nucleoid (Circular DNA)
- Ribosomes
- Cytoplasm
- Flagellum
- Cell wall
How big are eukaryots?
10-100 micrometers
How big are prokaryotes?
0.1 - 5.0 micrometers
Where are cells present?
In all living things
How many types of cell are there and what are they called?
- Prokaryotic
- Eukaryotic
What are cells measured in?
Micrometers
What are the sub-cellular structures are found in the Eukaryotic cells?
- Cytoplasm
- Cell Membrane
- Nucleus
What are the sub-cellular structures are found in the Prokaryotic cells?
- Plasmids
- Single DNA Loop
- Cell Membrane
What is standard form?
A way of making it easier to write very big and very small numbers.
How do you multiply numbers in standard form?
- Multiply the leading numbers.
- Add the powers.
- Change into the correct format.
- E.g. (3 x106) x (3 x104) = 9 x1010
How do you divide numbers in standard firm?
- Divide the leading numbers.
- Subtract the powers.
- Change into the correct format.
- E.g. (6 x107) ÷ (2 x103) = 3 x104
The prefixes (e.g. “kilo-“ or “centi-“) show the magnitude (size) of a value (or number). They can be put before different types of units. Here, we are using the unit for distance (metres, m) …
1 km = 1 kilometer = [103 m] = 1 000m
1 cm = 1 centimeter = [10-2 m] = 0.01 m
1 mm = 1 millimeter = [10-3 m] = 0.001 m
1 µm = 1 micrometer = [10-6 m] = 0.000001m
1 nm = 1 nanometre = [10-9 m] = 0.000000001 m
Which is larger… Eukaryotic of prokaryotic?
Eukaryotic
What type of cell are bacteria?
Prokaryotic
What are ribosomes responsible for synthesising? (making)
Proteins
What is the process of taking a plant cutting?
- Cut a small section off a plant stem
- Plant the section you have cut
- Some cells in the plant stem differentiate and create new root tissue.
- This allows a new plant to grow
What is the function of the cell wall in plant cells?
Surrounds the cell and increases the structural strength.
What is the function of the cell membrane in plant cells?
Separates the interior of the cell from the environment outside.
What is the function of mitochondria in plant cells?
The ‘powerhouses’ of the cell
What is the function of chloroplasts in plant cells?
Contain chlorophyll for photosynthesis.
what is the function of the vacuole in plant cells?
Fluid-filled sac that stores water. Keeps the cell turgid.
What is the function of Cytoplasm in plant cells?
Where most of the cell’s chemical reactions take place.
What is the function of the nucleus in plant cells?
The control centre of the cell.
What is the function of ribosomes?
Responsible for synthesising (making) proteins.
What do some bacterial cells have? (Prokaryote)
Flagella
What is the function of Flagella?
Movement
What are flagella?
Whip-like structures used for movement
What process happens in the mitochondria?
Aerobic respiration
What are mitochondria responsible for providing to the cell?
Energy
What are the structures of bacterial cells?
- Bacterial cells all have
- Cell walls.
- Cytoplasm
- Flagella
- Plasmids
When does differentiation primarily happen in an animals life?
During an organism’s development
What is cell differentiation?
A process where a cell gains new sub-cellular structures (structures inside a cell) in order to perform a specific function. When this happens the cell becomes ‘specialised’
What do muscle cells contain lots of and why?
mitochondria, which allow them to generate lots of energy. Protein fibres within the cell can contract, allowing the muscle to move.
What are sperm cells specialised for?
specialised so they are able to fertilise the egg. To do this they need to travel long distances - relative to their size - to reach the egg, then break through to the egg and fertilise it (combine the sperm DNA with the egg DNA)
Where does cell specialisation mainly happen in humans?
The embryo
when do plant cells differentiate?
Throughout their lives
What are the nerve cells surrounded by and why?
Nerve cells are surrounded by a myelin sheath which stops the electrical signals from leaking out of the nerve cell
What does the sperms head contain?
The sperm cell’s nucleus, which carries one half of an organism’s genetic material. It also contains an enzyme needed to penetrate (break into) an egg cell.
What is the sperms tail used for?
This is used for the cell’s motion.
what is the sperms middle section used for?
Is filled with mitochondria to provide energy for the sperm to travel a long distance to reach the egg.
Are root hair cells prokaryotes or eukaryotes?
Eukaryotes
What are root hair cells not used for?
Photosynthesis
Are root hair cells specialised?
Yes
In which two ways are root hair cells adapted to their function?
- No chloroplasts
- Long projections
What is lignin?
A substance that strengthens the cell walls of xylem cells
In plants, lignin is used by what cells.
Xylem
What are xylem specialised for?
To transport water up the stem and into he leaves
What are phloem specialised for?
Transporting food to parts of the plant where they are needed.
What are xylem vessels made of?
A series of connected dead xylem cells
What are phloem vessels made up of?
Columns of living cells
What cells is found in plants but does not contain chloroplasts?
Root hair cells
What must the plant transport to be able to survive?
Water and nutrients
What two variables matter the most in microscopy?
Magnification and resolution
What does magnification tell us?
How many times larger an image is seen through a microscope is compared to the the real object
What is resolution?
The ability to distinguish between two or more objects that are close together
Name some objects only visible through microscopes?
- Cell membrane
- Xylem cells
- Ribosomes
A cell has a diameter of 0.002cm. An image of the cell viewed through the microscope has a diameter of 6cm. What is the magnification?
6/0.002 = x3000
What is the equation for magnification?
Magnification = size of the image/size of the real objects
When was the electron microscope first used?
1933
How do light microscope work?
By passing light through a specimen, creating a magnified image, using lenses
When was the first light microscope with two lenses made??
16th century
How good is the resolution of a light microscope?
Has a resolution better then the human eye itself
What did lift microscopes allow us to see for the first time?
Bacteria
What did the light microscope allow us to see
- Bacteria
- Plant cells and animal cells as objects
What can’t light microscopes show us?
Sub-cellular structures apart
How do electron microscopes work?
By passing electrons through the specimen
How good is the resolution of an electron microscope?
They can now relive distances of 1nm (better resolution) with magnifications of x500,000
What does the high level detail of electron microscope allow scientist to do?
- see sub-cellular structures more clearly
- study how structures such as mitochondria, chloroplasts and ribosomes function
When using a microscope what is used to give contrast the o features of the cells, to make them visible?
A stain, such as iodine
When using a light microscope how do you focus?
By using the lowest power objective lense. Increase the power and refocus.
How can microorganisms be grown?
- As colonies on an agar gel plate
- In a solution of a nutrient broth
What does a nutrient broth contain?
- Carbohydrates as an energy source
- minerals
- Sometimes other chemicals
In what two mediums (materials) can microorganisms be grown?
- nutrient broth
- Agar gel plate
What is a risk of growing cultures of Bacteria?
As well as jeopardising the results of the investigation, CONTAMINATION is a serious health and safety risk as it lets other, potentially harmful, bacteria grow
What are some potential sources of contamination when growing cultures of bacteria?
- Skin
- Air
- Soil
- Water
How do we prevent contamination when growing cultures of bacteria?
For investigations into antibiotics to be useful, the cultures must be pure (do not contain bacteria that are not being investigated)
What growing bacterial cultures, what is an independent variable?
The choice of antibiotic/antiseptic
What is the maximum temperature at which cultures should be incubated at in schools and why?
25 degrees Celsius, because it refuces the risk of harmful bacteria growing
How are petri dishes stored?
With a taped lid to prevent air from getting into he Petri dish and upside down to prevent condensation forming on the lid and then dripping into the agar.
How do you prevent air from getting into the Petri dish when transferring bacteria?
The lid must be quickly removed and replaced when transferring bacteria to the agar using the inoculating loop
How do you sterilise inoculation loops?
By passing it through a flame to remove bacteria
How do you sterilise solutions and agar?
Boiling
Aseptic technique is used to prevent contamination. What does it involve?
- Flames
- Temperature
- Using life
- Boiling
How do bacteria multiply?
Through simple cell division, binary fission, in which one cell devises to produce two cells
How do you estimate a future population of bacteria?
By multiplying he current population by two for every mean division time (time it takes for the bacteria to divide) that passes.
-Divisions can pc our as frequently as one every 20 minutes in ideal conditions
How is the area of a circular colony of bacteria calculated?
Pi times the square of the radius
A colony of bacteria forms a circle with a diameter of 1.6cm. What is the area of the colony? (Pi = 3.141)
- Radius = 1.6/2?=0.8cm
- Pi X 0.8 squared
- = 2.01 cm squared
What can cultures of bacteria be used to investigate?
Antibiotics and disinfectants
What is a culture?
A substance that provides the nutrients for the artificial growth of bacteria and other cells, such as nutrient broth of agar gel is a Petri dish
What is agar?
A jelly mass from algae that is used to culture microorganisms
What are antibiotics?
Medication used to kill disease-causing bacteria inside the body
What is a Petri dish?
A round, shallow dish used to grow bacteria
A strain of bacteria has a mean division time of 30 minutes. A group of 4 bacterial cells is left to grow. How many cells will there be at the end of 4 hours?
1024
What do chromosomes contain a large number of?
Genes
What do genes specifically code?
Proteins
The stages of the cell cycle are…
- Initial growth
- Mitosis
- Cell division
Which structures are produced In the initial growth stage of the cell cycle?
- Sub-cellular structures
- Ribosomes
- Extra chromosomes
- Mitochondria
Why is it so important that the daughter cells, produced during mitosis, have the same chromosomes as each other?
It is important for the process m that require identical cells to be produced, for example the growth and repair of tissues and asexual reproduction
In the cell cycle, what process occurs before chromosomes duplicate?
Cell growth and the duplication of sub-cellular structures
How many types of sex cell are there and what are they called?
- ..
- Egg
- Sperm
Mitosis is the process that produces two ……….. cells.
Identical
What does each gene tell us to make?
A specific protein
During mitosis two sets of …………… are pulled to opposite ends of the cell. Then the …………. divides into two.
- Chromosomes
- Nucleus
Do body cells of sex cells have more chromosomes?
Body cells have 2 times as many chromosomes as sex cells
What cells are undifferentiated?
Stem cells
Stem cells are used in cloning. Why must we used stem cells, rather than normal cells, to clone and animal?
- Stem cells are undifferentiated cells, meaning they differentiated into any kind of cells
- By using a stem cell, we can use cloning techniques, such as replacing the stem cell’s genome, to ensure that he entire cloned animal contains only the desired DNA
What are some disadvantages to stem cells?
- Ethical beliefs
- The transfer of viral infections
Stem cells are undifferentiated cells found in…
- Bone Marrow
- Embryos
- Plant Meristems
What are the two types of stem cells in humans?
- Embryonic
- Adult
What is therapeutic cloning? How is it effective?
A process that produces an embryo with the same genes as the patient. Stem cells taken from this embryo will have the same DNA as the patient, so the patients body will not reject the stem cells of body cells made from the stem cells
What is diffusion?
The net movement of particles from an area of high concentration to an area of low concentration
How does membrane surface area affect the rate of diffusion?
He larger the surface area of the membrane that a substance is diffusing through (e.g. the membrane around a cell), the faster the rate of diffusion.
How does temperature affect the rate of diffusion?
The higher the temperature, the faster the rate of diffusion
How does the concentration gradient affect the rate of diffusion?
- The concentration gradient is linked to the different in concentration between two areas
- The bigger the difference in concentration between two areas, the greater the concentration gradient and the faster the rate of diffusion
What factors effect diffusion?
- Concentration gradient
- Temperature
- Membrane surface area
Small organisms normally have higher surface area to volume ratios than larger organisms. What does this mean?
That diffusion can happen through a larger area in small organisms. This makes diffusion useful for transporting molecules through a small organism
The higher the surface are to volume ratio, the higher the…..
Rate of diffusion
How are alveoli specialised to transfer gases in the lungs?
They have a large surface area
Name two examples of passive transport…
- Diffusion
- Osmosis
Wha is active transport?
The net movement of particles against the concentration gradient. -Requires energy
What are exchange surfaces?
Surfaces that are adapted to maximise the efficiency of gas and solute exchange across them
How are leaves adapted?
For exchanging carbon dioxide and oxygen between the leaves and the surrounding air
Why is a thin membrane a useful adaptation of an exchange surface?
A thin membrane reduces the diffusion distance
Wh is a large surface area a useful adaption of an exchange surface?
A large surface area allows more of a substance to diffuse at the same time
What are exchange surfaces densely packed with? Why?
Blood vessels. These replenish the blood supply to maintain a high concentration gradient by bringing in new blood as diffusion starts to even out the concentrations
What happens, in animals, if a gas is exchanged?
The surface is ventilated (throw breathing) to maintain a high concentration gradient and increase the rate of exchange
What is the small intestine adapted for?
Adapted for exchanging nutrients between denigrated food in the small intestine and the blood
What are the lungs adapted for?
Adapted for exchanging carbon dioxide and oxygen between the blood and air
What are girls adapted for? (Fish)
Adapted for exchanging oxygen that is dissolved in water, with the carbon dioxide in a fish’s bloodstream
What are roots adapted for?
Adapted for taking up both water and minerals from the soil around them
What are leaves adapted for?
Adapted for exchanging carbon dioxide and oxygen between the leaves and the surrounding air
Name some specialised exchange surfaces…
- Roots
- Leaves
- Lungs
- Small intestine
- Gills
What is a partially permeable membrane?
A membrane that allows water through, but won’t let large molecules dissolved in water pass through
What is osmosis?
The diffusion of water across a partially permeable membrane from a dilute solution (high concentration of water) to a concentrated solution (low concentration of water)
What is the independent variable?
The variable you control/change
It is changed to see how the dependent variable will change
What is the dependent variable?
The variable that you measure as an outcome of the experiment
Name the substances that are absorbed via active transport in the following structures:
- Guts of humans…
- Roots is plants…
- Sugar
- Minerals
During osmosis concentrations becomes the ………. on both sides of the membrane
Same
During osmosis water moves from a ……….. solution to a more ……….. concentrated solution
- Dilute
- Concentrated
Mineral absorption in plants: What are mineral ions necessary for?
Healthy growth
Sugar absorption in human gut: What are sugar molecules needed for?
Cell respiration
What is passive transport?
A naturally occurring phenomenon that does not require the cell to expend energy to accomplish the movement
What is a hypertonic solution?
The concentration of solutes in the solution outside the cell is higher than the concentration inside the cell
