Cell division Flashcards
What does the cell membrane do? (1 mark)
It controls the movement of substances in and out of cells
What is the function of the cytoplasm? (1 mark)
It is a gel-like substance where chemical reactions inside the cell take place (e.g. anaerobic respiration)
What is the function of the nucleus (or DNA)? (1 mark)
It contains genetic material and controls cell activities
What is the function of ribosomes? (1 mark)
They are the site of protein synthesis
What are some differences between prokaryotic and eukaryotic cells? (4 marks)
The genetic material (DNA) in eukaryotic cells is enclosed within a nucleus. Whereas, the genetic material in prokaryotic cells is not enclosed within a nucleus, but is rather found as a single loop of DNA within the cytoplasm.
Eukaryotic cells vary in size, usually between 10 and 100 µm. Whereas, prokaryotic cells are smaller in comparison, measuring around ~ 1 µm in size
What are the cell membranes of all prokaryotic cells surrounded by? (1 mark)
A cell wall (usually made from a substance called peptidoglycan)
What are some examples of eukaryotic cells? (4 marks)
animals and plant cells, fungi and protists
What are some examples of prokaryotic cells? (1 mark)
Bacterial cells
Where is the genetic material (DNA) in prokaryotic cells found? (2 marks)
The genetic material is found as a single loop of DNA within the cytoplasm
Additional smaller, circular pieces of DNA is found as plasmids
What do scientists measure the size of cells in? (1 mark)
Micrometres (µm)
What is the order of measurement? (1 mark)
metre (m)
millimetre (mm)
micrometre (µm)
nanometre (nm)
How do you change between the measurements? (1 mark)
/ 1000 or x 1000
What is the size of a palisade mesophyll cell? (1 mark)
70 µm
What is the size of a cheek cell? (1 mark)
65 µm
What is the size of mitochondria and chloroplast? (1 mark)
1.5 µm
What is the size of cholera bacterium? (1 mark)
1.5 µm
What is the size of the HIV virus? (1 mark)
100 nm
How do you work out the order of magnitude? (2 marks)
order of magnitude is 10 to the power of n
e.g. 100x greater = 10^2 = 2 orders of magnitude
What is the purpose of mitochondria? (1 mark)
It is the site of aerobic respiration and energy release
What is an organelle? (2 mark)
It is a subcellular structure that is specialised to carry out a particular function or process within a cell
Why are some organelles not membrane bound? (2 marks)
Some organelles are more solid structures that are not fluid-filled (e.g. ribosomes and the cell wall)
What are some examples of organelles in animal cells? (5 marks)
The nucleus Cell membrane Mitochondria Ribosomes Cytoplasm
What are some examples of organelles in plant cells? (2 marks)
Cell wall made of cellulose
A permanent vacuole filled with cell sap
What is the function of a cell wall? (1 mark)
It is made of cellulose to strengthen the cell
What is the purpose of chloroplast? (1 mark)
It contains chlorophyll (green pigment to absorb light energy) and is the site for photosynthesis
What is the purpose of a permanent vacuole? (2 marks)
It is filled with cell sap (a solution of sugars and salts dissolved in water) to keep cells rigid.
It also stores certain materials (e.g. salts and minerals)
What do light microscopes use? (1 mark)
They use light and lenses to form a magnified image of a specimen
What are light microscopes used for seeing? (1 mark)
to see images of cells and large subcellular structures (like nuclei and vacuoles)
When were the first light microscopes invented? (1 mark)
In the 17th Century
Which scientists used microscopes to develop our first understanding of cells? (2 marks)
Anton van Leeuwenhoek and Robert Hooke
When were the first electron microscopes developed? (1 mark)
in the first half of the 20th Century
What do electron microscopes use?
They use beams of electrons, rather than light, to visualise specimens
Why do electron microscopes use an electron beam? (2 marks)
The wavelength of an electron beam is much smaller than that of visible light, which gives electron microscopes a much higher resolution and magnification
What are electron microscopes used for? (2 marks)
To study cells in much finer detail (e.g. subcellular structures such as the mitochondrion)
They also help to develop an understanding of the structure of the nucleus and cell membrane
What is the equation for magnification? (1 mark)
actual size = image size / magnification
