Cells Flashcards
Function of the nucleus
Stores DNA as chromosomes
Function of nuclear membrane
Surrounds nucleus
Function of cell membrane
Surrounds cell. Controls what enters and leaves the cell and is selectively permeable
Function of cell wall
Made of cellulose. Surrounds cell. Made for protection and support
Function of chloroplasts
Contain chlorophyll which trap sunlight to make energy by photosynthesis
Function of the vacuole
Contains sap and is surrounded by the membrane
Function of chromosomes
Found in nucleus. Contains DNA from parents and pass this information on to next generation
Function of cytoplasm
Jelly-like watery solution which contains cell organelles and dissolved proteins. Chemical reactions occur here
Function of mitochondria
Aerobic respiration occurs here
Method for observing cheek cells
1.Rub swab on inside of cheek to collect cells
2.Rub swab across slide to transfer cells
3.Add one drop drop of methylene blue stain to smear
4.Lower cover slip over cells using forceps
5.Observe cells under microscope
Method for observing onion cells
1.Peel a layer of onion epidermis using tweezers
2.Place cells on slide
3.Add 1-2 drops of iodine to stain cells
4.Lower cover slip over cells using forceps
5.Observe cells under microscope
What does selectively permeable mean
It allows useful substances e.g oxygen and glucose to enter cells and waste e.g urea and carbon dioxide to leave cells. It also prevents the passage of large molecules e.g proteins
Factors that affect the movement of substances into cells
1.Diffusion gradient
2.Permeable layer
3.Large surface area
4.Thin membrane
5.Temperature
How temperature affects movement of substances into cells
High temperature increases kinetic energy making molecules move faster
Diffusion definition
The random movement of gases or liquids from a high to low concentration down a diffusion gradient
What gases are involved in human respiration
Oxygen into blood cells and carbon dioxide out of blood cells
Where does respiration occur in humans
The alveoli
What gases are involved in plants photosynthesizing
Carbon dioxide into the leaf and oxygen out of the leaf
What gases are involved in plants respiring
Oxygen into the leaf and carbon dioxide out of leaf
What is involved in the absorption of food
Nutrients e.g glucose and amino acids
Surface area to volume ratio
- The larger the surface area the more oxygen can diffuse into the cells
-As cells get bigger the surface area and volume increases
What adaptation have been made in multi celled organisms to create a large surface area
Special gas exchange organs that create a large surface area e.g alveoli in lungs
How is the problem solved of the gas exchange surface being far from body cells
A transport system is needed e.g the circulatory system
Why are cells organised into tissues, organs and systems
1.Improves exchange with environment e.g oxygen and carbon dioxide
2.Helps with transport around the body e.g glucose
3. Helps communication between cells e.g nerve and muscle
Cell definition
Basic unit of life e.g nerve cell
Tissue definition
Cells with the same specialised structure and function grouped together
Organ definition
Made up of different tissues to carry out a function
System definition
Made up of different organs working to carry out a function
Organism definition
Made up of different systems working together
Function of nervous system and its main organs
-Responds to stimuli and makes responses
-Main organs are the brain, spinal cord and the receptors
Function of reproductive system and its main organs
-Production of young
Main organs are the ovaries, uterus and testes
Function of excretory system and its main organs
-Maintaining water levels and removing poisonous wastes
-Main organs are kidneys, urethra, ureter and bladder
Function of circulatory system and its main organs
-Transports gases, nutrients and viruses around the body
-Main organs are the heart and blood vessels
Magnification definition
The number of times the image is bigger than the actual size
Magnification equation
Image/actual
How to convert from metres to micrometres
X1000000
How to convert from millimetres to micrometres
X1000
How to convert from micrometres to millimetres
Divide by 1000
How to convert from micrometres to metres
Divide by 1000000
How to calculate the magnification of a microscope
Eyepiece mag X Objective mag
What is a resolution
The ability a microscope has to distinguish detail
Light microscope
-Magnification of x1500
-Resolution of 0.2 micrometres
-Can see large cell structures
-Uses light
Electron microscope
-Beams of electrons pass through the specimen
-Can see cell structures in detail
-Magnification of X500000
-Resolution of 0.0001 micrometres apart
What are stem cells
Simple unspecialised cells in plants and animals that have the ability to divide to form cells of a specific type
Where are stem cells found
-The bone marrow of adults
-Umbilical cord/ placenta/ embryo
What abilities do stem cells have
-They can continue dividing by cell division
-To differentiate into a wide variety of specialised cell types
What 2 situations can embryonic stem cells be collected
-From embryos not being used for fertility treatment
-From the umbilical cord/ placenta during pregnancy
Where are stem cells found in plants
The apical meristems (growing regions)
Stem cells in medicine
-Chemotherapy and radiotherapy destroy white blood cells and stop bone marrow production
-A transplant of bone marrow containing stem cells from a matching healthy donor
-The stem cells divide and produce healthy blood cells in in the patient
Negatives of stem cells
-No white blood cells means no immune system and more chance of infection
-Stem cells may divide in an uncontrolled way and produce tumours or unwanted cell types
-Religious reasons/ rights of unborn child
