Topic 1 - Cells Flashcards
Name all the features of an animal cell.
- cytoplasm
- nucleus
- mitochondria
- cell membrane
Name all the features of a plant cell.
- cytoplasm
- cellulose cell wall
- cell membrane
- Nucleus
- vacuole
- mitochondria
- chloroplasts
Why is he nucleus called the control centre of the cell ?
It’s surrounded by nuclear membrane and these contain chromosomes. Which then contain DNA.
What’s the purpose of a cellulose cell wall?
Stiff structure, and it provides support
What’s the purpose of the vacuole ?
Contains cell sap, when it’s full it pushes the cell membrane against the cell wall making the cell rigid.
What are the purpose of chloroplasts ?
Contain chlorophyll , which traps light and makes food during photosynthesis.
List the features of a bacterial cell.
- circular chromosome
- plasmid
- non-cellulose cell wall
What are the plasmids in the bacterial cell ?
Small rings of DNA
List the steps taken to prepare a slide to look at onion cells.
1: peel a thin transparent layer of onion off with forceps
2: place on the slide with a few drops of water.
3: add iodine to stain the cells to make them easier to see.
4: lower coverslip over the epidermis( make sure no air bubbles are present)
What is the (did)advantages to using a low power objective lens ?
Advantages:
• greater field of view
• easier to focus
Disadvantages:
• only see a little detail
What are the (dis)advantages of using a high power lens?
Advantages:
•see in greater detail
Disadvantages
• harder to focus
• can be damaged easily
• lower field of view
What’s the equation for magnification?
Observed
——————————-
Actual x magnification
State how to convert mm - um
mm - m
And the standard form of mm and um in m
Multiply um by 1000 to get mm
Multiply mm by 1000 to get m
mm = 10^-3 um = 10^-6
What’s a microscopes resolution ?
The ability of the microscope to let us see detail.
How do electron microscopes work?
Pass a beam of electrons through a specimen, to investigate the structures inside cells.
What is meant by the term selectively permeable ?
Allows substances need by the cell to enter and lets waste products not needed by the cell to exit the leaf.
What’s the definition of diffusion?
The random movement of a substance from where it is in a high concentration to where it’s in a low concentration.
Name 3 factors that affect the rate of diffusion.
1: the difference in the concentration between the high and low conc areas. The larger the difference the faster the diffusion
2: temperature
3: larger SA
How does the SA/V ratio affect the rate of diffusion ?
The bigger the volume of the cell the greater amount of substances the cell needs for its reactions. The greater the SA the more of these substances can diffuse into the cell.
How do large active multi celled organism create a large SA/V ratio.
They have developed special gas exchange organs (lungs) to greatly increase the SA.
Definition of a tissue.
Cells with the same specialised structure and function which are grouped together.
Definition of an organ.
Made of several types of tissue for a particular function.
Definition of an organ system.
Organs which operate together to carry out a particular function are linked together in organ systems.
What are stem cells ?
Unspecialised cells.
