Biology - Cell Biology Flashcards
What does a eukaryotic cell have that a prokaryotic cell doesn’t?
A nucleus
Is a plant cell a prokaryotic cell or eukaryotic cell?
Eukaryotic cell
Is a bacterium a prokaryotic cell or eukaryotic cell?
Prokaryotic cell
Where does aerobic respiration take place in a cell?
Mitochondria
What part of a cell controls what chemicals enter and leave the cell?
Cell membrane
What part of the cell contains the DNA?
Nucleus
In what part of the cell do the majority of chemical reactions take place?
Cytoplasm
Name any structures found in plant cells but not animal cells.
Chloroplasts, large central vacuole, cell wall, starch granules
What does a ribosome do?
Makes proteins
What is resolution?
How close two points can be but not blur into each other
What is magnification?
How many times bigger the image is than the original object
True or false? Electron microscopes have greater magnification and resolution than light microscopes.
True
True or false? Electron microscopes can produce colour images.
False
Which microscope is better for use on live cells, light or electron?
Light (cells must be dead in electron microscopes)
Why is iodine added to plant cells, and methylene blue added to animal cells, before looking at them under a light microscope?
They stain the structures in the cells so they are easier to see
How many μm in a mm?
1000
If a cell has a width of 100μm and is magnified x 200, what is the width of the image in mm?
Image size = Magnification x Real size = 200 x 100μm = 20 000 μm.
20 000 μm / 1000 = 20 mm.
Remember: 1000 μm = 1 mm.
Which cells in plants are specialised for absorbing water and minerals from the soil?
Root hair cells
What is the function of a sperm cell?
To carry the father’s DNA to the mother’s DNA in the egg to fertilise it
What does an xylem cell do?
Transports water and minerals from the roots to the leaves
How is an xylem cell specialised for its function?
It is hollow
What does a nerve cell (neurone) do?
A nerve cell carries signals from one part of the body to another
How is a nerve cell adapted to its function?
It is long and has branches at its ends to connect to other nerve cells
How many pairs of chromosomes are found in a normal human cell?
23 pairs (46 in total)
Which of the following do chromosomes contain? A) Mitochondria B) Cytoplasm C) Genes D) Amino Acids
C) Genes
If a cell divides by mitosis, will the two daughter cells be identical to the original cell?
Yes
If a cell divides by meiosis, will the four daughter cells be identical to the original cell?
No
Is mitosis used to produce gametes (sex cells)?
No
State three factors that may affect the size of a bacterial colony
e.g. Temperature, nutrients available, competition from other microorganisms
If a bacterial cell has a mean division time of 40 minutes, how many cells will it have produced after 200 minutes?
200 divide 40 is 5. So it will divide 5 times. 2^5 = 32, so 32 cells will be produced.
If a bacterial cell has a mean division time of 20 minutes, how many cells will it have produced after 2 hours?
2 hours = 120 minutes. 120 divide 20 is 6. So it will divide 6 times.
2^6 = 64, so 64 cells will be produced.
What is an agar plate?
A petri dish and a jelly (source of nutrients)
What is the zone of inhibition when you add antibiotic discs to an agar plate?
The region around each disc where the bacteria are killed off
Why are agar plate cultures incubated at a maximum temperature of 25°C in schools?
Harmful bacteria are more likely to grow above this temperature
Why is it important to sterilise an agar plate before conducting a culturing experiment?
So no unwanted microorganisms grow and compete with your culture.
What is a stem cell?
A cell which can become one of many different types of cell
Where can stem cells be found in an adult human?
Bone marrow
Where can stem cells be found in a plant?
Meristem
What is a risk of stem cell therapy?
Contamination could pass a virus on to the patient
Mr Correct is worried about a plant disease that could spread to the crops on his farm. How could he use stem cells to help?
Use stem cells to grow crops of identical plants with disease resistance
During a heart attack there is damage or death of heart muscle. How can embryonic stem cells help treat a patient after?
Embryonic stem cells could develop into heart muscle cells and replace the damaged cells
What are the ethical pros and cons to embryonic stem cell therapy?
Pros: helping patients. Cons: embryos are human life, so it is wrong to take stem cells from them.
What is diffusion?
The spreading of particles from an area of high concentration to low concentration
True or false? The bigger the concentration gradient, the faster the rate of diffusion.
True
True or false? The higher the temperature, the faster the rate of diffusion.
True
True or false? The larger the particle, the faster the rate of diffusion.
False
True or false? The larger the surface area, the faster the rate of diffusion.
True
When will diffusion stop?
When the particles are evenly spread everywhere
Does diffusion require energy input?
No – it is a passive process
What is osmosis?
Diffusion of water from high water concentration to low water concentration across a partially permeable membrane
True or false? Oxygen entering the blood from the lungs is an example of osmosis.
False – this is diffusion
If you put a potato in pure water what will happen to its mass and why?
The water concentration is higher outside, so water will diffuse in by osmosis and the mass will increase
If you put a potato in a concentrated salt solution what will happen to its mass and why?
The water concentration will be lower outside, so water will diffuse out by osmosis and the mass will decrease
What is the formula for percentage change in mass?
(Final Mass – Original Mass)/Original Mass x 100%
What is active transport?
The movement of particles from an area of low concentration to high concentration, requiring energy from respiration
Why do root hair cells need to use active transport to take in minerals?
The root absorbs so many minerals, the concentration is higher in the root than the soil, so it must use active transport to continue absorbing
If a cell has to carry out a lot of active transport, which organelle is it likely to contain a lot of?
Mitochondria to supply the energy for active transport
If an organism gets larger, does its surface area to volume ratio increase or decrease?
Decrease
Why do single-celled organisms not require lungs to exchange gases with their environment?
Their surface area to volume ratio is very large so enough gas can diffuse across their cell membrane
a) What is the surface area of a 3cm x 3cm x 3cm cube?
b) What is its volume?
c) Hence, what is the surface area to volume ratio of the 3cm x 3cm x 3cm cube?
a) Six sides. Each has area 3 x 3 = 9cm2. So total surface area is 54cm2.
b) 3 x 3 x 3 = 27cm3
c) 54 : 27 (simplifies to 2 : 1)
Which two gases are exchanged in a leaf?
Oxygen and carbon dioxide
What is the function of alveoli?
Diffusion of oxygen into the blood and carbon dioxide out
How are the alveoli adapted for their function?
Thin moist walls, large surface area, good blood supply
Coeliac disease can cause the villi in the small intestines to flatten. How might this affect the absorption of digested food into the blood?
This would reduce surface area so less digested food gets absorbed.
What adaptations does a leaf have to help gas exchange?
Stomata (pores), large flat surface, air spaces inside the leaf
What does the cell say?
The cell says OK.
How many cells are produced in mitosis?
Two
How many cells are produced in meiosis?
Four
What is the name of a cell produced by meiosis?
A gamete
What is the male gamete called?
Sperm cell
What is the female gamete called?
Egg cell
How many chromosomes does a human gamete have?
23
Does every gamete contain the same DNA?
No they each contain random mixes of the father’s and mother’s chromosomes present in the parent cell.
What is the difference between mitosis and meiosis?
Mitosis is normal cell division. It produces two identical daughter cells.
Meiosis is cell division to produce four gametes (sex cells), in a two stage process (i.e. cell division occurs twice). Each gamete has half the normal number of cell chromosomes. Each gamete contains different DNA.
