EOY B1 Flashcards
1m = cm?
100cm
1cm is mm
10mm
1mm is how many micrometers
1000
1 micrometer is nanometres
1000
How do electron microscopes work?
They use a beam of electrons to form an image
What type of electron microscope makes 2D images, with high mag and resolution?
Transmission electron microscope
What type of electron microscopes give dramatic 3D images but with lower mags?
Scanning electron microscopes
What is the equation for total mag?
Objective lens x ocular (eyepiece) lens
How do you use a microscope?
- Place specimen or object on to slide. This is called mounting.
- You may have to cut the object or stain it to make the features stand out or to see through it
- After, cover with a small, thin square of glass called a ‘cover slip’.
- Secure the slide to the stage with 2 clips.
- Turn large wheel (course focus) until stage is as close to objective lens as possible
- Turn turret to lowest mag (usually 4x) until lens is over slide
- Look down eyepiece lens (usually 10x mag)
- Turn course focus slowly until you see cells
- Turn fine focus until you see clearly
- Do again with next objective lens
Advantages of light microscope
Relatively cheap
Mag up to 2000x
Can be used almost everywhere
Disadvantages of light micro
Limited mag
Limited resolution
Advantages of electron micro
High mag up to 2000000x
High resolution
Can give 3D images
Disadvantages of electron micro
Expensive
Must have specific temp, pressure and humidity needed
Equation for mag
Image height / object height
Or
Size of image/ size of real object
What is resolution?
How is it measured?
How detailed an image is, high resolution = more detail image holds.
Is measured by shortest distance between 2 points that can be seen as 2 separate points by observer
Equation for magnification triangle
I (image size)
A (actual object size M (magnification)
I AM
What sub nuclear components are found in the animal cell?
Nucleus
Cytoplasm
Cell Membrane
Mitochondria
Ribosomes
What does the mitochondria do?
Structures in the cytoplasm where aerobic respiration takes place, releasing energy for the cell.
What do ribosomes do?
Where protein synthesis takes place, making all the proteins needed in the cell.
What are algae?
Simple aquatic organisms
Make their own food via photosynthesis and have similar features to plant cells.
They are now classified as part of the Protista kingdom
All plant and algal cells have a cell wall made of —
Cellulose
What are chloroplasts?
Green sub cellular structure
Contain chlorophyll which absorbs light so the plant can make food by photosynthesis.
What is a permanent vacuole?
Is a space in the cytoplasm filled with cell sap
This is important for keeping the cells rigid to support the plant
What is in a Eukaryotic cell?
Animal and plant cells
They all have a cell membrane, cytoplasm, genetic material enclosed in a nucleus.
The genetic material is called DNA and this forms structures called chromosomes that are contained within the nucleus
Give examples of eukaryotes
Humans
Animals
Plants
Fungi
Protista
Give example of prokaryote
Bacteria
What do bacterial cells have?
Cytoplasm
Cell membrane
Cell wall (not cellulose, murin)
Genetic material (not in nucleus)
Bacterial chromosome (single DNA loop in cytoplasm)
May also have extra small rings of DNA called plasmids. These code for specific features such as antibiotic resistance.
Some have a protective slime capsule
Some have a flagellum (long strand of protein that lashes out, so they can move around)
How do cells get specialised?
It gets different sub cellular structures that endangers it to carry out a specific function.
What is the function of a nerve cell?
Carry electrical impulses around the body of an animal
What adaptations do sperm cells have?
Long tail whips from side to side to help sperm move
Middle section is full of mitochondria which transfer energy needed for tail to work
The acrosome stores digestive enzymes for breaking down the outer layers of the egg
A large nucleus contains genetic info (haploid, only half of chromosomes)
What is sperm function?
Join with egg cell during fertilisation to form and embryo
What is function of egg cell?
Join with sperm cell to form embryo
Adaptations of egg cell
Cytoplasm contains nutrients or growth of early embryo
Haploid nucleus
Cell membrane changes after fertilisation so that only one sperm can enter
Contains yolk which provides food store for forming cell
Large and bulky
What is the function of ciliates cells?
Found in airways
Move mucus containing dust and particles up, out of airways
Also found in oviducts
What is function of red blood cell?
Carry oxygen around body for respiration
What is the function of a root hair cell?
Absorb water and minerals from the soil
What are the adaptations of root hair cells?
They greatly increase the surface area available for water to move into the cell
They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell
They have many mitochondria that transfer the energy needed for the active transport of mineral ions into the root hair cells
Give the last adaptation of palisade cells that didn’t fit on physical flash card
They have a large permanents vacuole that helps keep the cell rigid as a result of osmosis. When lots of these rigid s are arranged together to form photosynthetic tissue, they help support the stem. They also keep the leaf spread out so it can capture as much light as possible.
What is the function of xylem cells?
Carries water and mineral ions from roots to highest leaves and shoots. It also supports the plant.
How are xylem cells adapted
The xylem cells are alive when they are first formed but a special chemical called lignin builds up in spirals in the cell walls. The cells die and form long hollow tubes that allow water and mineral ions to move easily through them, from one end of the plant to the other.
The spirals and rings of lignin in the xylem cells make them very strong and help them withstand the pressure of water moving up the plant. They also help support the plant stem.
They have no cytoplasm, are impermeable to water, have tough walls with no top and bottom
What is the function of phloem cells?
Carries food made by photosynthesis around the plant (sucrose and amino acids) from leaves and other parts of the
What are adaptations of phloem cells?
The cell walls between cells break down to form sieve plates. These allow water carrying dissolved food to move freely up and down tubes to where it is needed
Phloem cells lose a lot of their internal structures but they are supported by companion cells that help keep them alive. The mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the plant in phloem.
What is diffusion?
Is the spreading out of the particles of a gas or of any substance in solution (a solute). This results in the net movement (overall movement) of particles. The net movement is from an area of higher concentration to an area of lower concentration of the particles (molecules or ions). The motion of the particles causes them to bump into each other, and this moves them all around.
What is diffusion? (Short)
The net movement of particles from an area of higher concentration to and area of low concentration
What is net movement?
Movement of most of the particles as a group.
Where does diffusion happen (states of matter)
Gases and liquids (fluids)
What does partially permeable mean?
Only some molecules can diffuse through this barrier
What is meant by diffusion is a passive process?
It means it doesn’t require energy from the cell.
If there is a big difference in concentration between two areas, diffusion will take place —
Quickly
What is equation for net movement?
Net movement = Particles moving in - particles moving out
The diffference between two areas of concentration is called the concentration gradient. The bigger the difference, the — the concentration gradient and the — the rate of diffusion. In other words, diffusion occurs — a concentration gradient.
Steeper
Faster
Down
What affects rate of diffusion?
3 things-
Concentration gradient (the difference in concentration between 2 places)
Temperature
Surface area
What kind of substances move in and out of cells through diffusion?
Simple sugars like glucose
Gases like oxygen and carbon dioxide
Waste products such as urea from the breakdown of amino acids in your liver
Respiration- air into lungs into red blood cells
What is the most common adaption to make diffusion easier?
Increase the surface area of the cell membrane by folding up the membrane of the cell or the tissue lining of an organ
What is osmosis?
A special case of diffusion
Net movement of water molecules across a partially permeable membrane from an area of high water potential to low water potential
It is a passive process
How is water potential measured?
Water molecules collide with membrane, applying pressure to membrane. This pressure is called water potential and the unit is kilopascal.
When does osmosis stop?
When both sides have the same water potential and have reached equilibrium, osmosis stops. Water molecules will still move but the net movement will be 0.
What has the highest possible water potential?
0 kilopascals- pure water
Charged or large particles can’t pass membrane.
What is a dilute solution?
A dilute solution of sugar contains a high concentration of water (the solvent). It has a low concentration of sugar (the solute).
What is a concentrated solution?
A concentrated sugar solution contains a relatively low concentration of water and a high concentration of sugar
What does it mean: isotonic
If the concentration of solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell .
What does it mean: hypertonic
If the concentration of solutes in the solution out Osidge the cell is higher than the internal concentration, the solution is hypertonic to the cell
What does hypotonic mean?
If the concentration of solutes in the solution outside the cell is lower than the internal concentration, the solution is hypotonic to the cell
Why do plants need osmosis?
To support their stems and leaves. Water moves into plant cells by osmosis. This causes the vacuole to swell, which presses the cytoplasm against the plant cell wall. The pressure builds up until no more water can physically enter the cell, this pressure is called turgor.
What happens if the solution surrounding the plant cells is hypertonic to the cell contents?
Water will leave by osmosis. The cells will no longer be firm and swollen, they become flaccid (soft) as there is no pressure on the walls.
What is plasmolysis plants?
If more water is lost, the vacuole and cytoplasm shrink and eventually the cell membrane pulls away from the cell wall. This is plasmolysis.
Plasmolysis is only seen in lab experiments these cells die quickly if not changed
What is active transport?
The movement of molecules across a cell membrane from an area of low concentration to high concentration and requiring energy from cellular respiration.
What is surface area to volume ratio?
It makes a big difference to the way animals can exchange substances with the environment. Surface area to volume ratio is also important when you consider how energy is transferred by living organisms, and how water evaporates from the surfaces of plants and animals.
What happens when a living organism gets bigger?
As living organisms get bigger and more complex, their surface area to volume ratio gets smaller. This makes it increasingly difficult to exchange materials quickly enough with the outside world:
- Gases and food molecules can no longer reach every cell inside the organism by simple diffusion
- Metabolic waste cannot be removed fast enough to avoid poisoning cells
How can the effectiveness of an exchange surface be increased?
- Having a large surface area
- Having a thin membrane
- In animals an efficient blood supply moves the diffusing substances away from the exchange surfaces and maintains a steep concentration gradient.
- In animals, being ventilated makes gas exchange more efficient by maintaining steep concentration gradients
What is the function of meristem tissue in the growth of a plant?
They are undifferentiated
Meristem cells divide by mitosis
To give rise to new tissues
Why are Troy hair cells considered specialised cells?
They have undergone differentiation
The have a specific role in the plant
Give an example of a metabolic reaction-
- Formation of lipid molecules from a molecule of glycerol and three fatty acid molecules
- Reactions of photosynthesis
- Reactions of respiration
