Cell Structure and Transport Flashcards
Features of a Light Microscope
- 17th Century
- Beam of light
- 2000x
- Cheap
- Little training
- Easy to move
- Colour
- Small
- Passes through air
Features of an Electron Microscope
- 1930s
- Beam of electrons
- 2,000,000 x
- Expensive
- Need training
- Hard to store
- Black and white
- Big
- Passes through vacuum
Examining plant cells under a light microscope practical
1) Rotate lenses so that low power is in line with stage
2) Focus coarse so stage is close to lense
3) Place slide in middle of sage where light passes through
4) Focus slide by adjusting coarse
5) Draw low power image of what you see
6) Don’t look directly into light to damage eyes, take care when handling slides and placing plant cell
Obtaining cell onto slide practical
1) Put small drop of water on slide
2) Peel very thing layer of onion skin with scalpel and tweezers
3) Use forceps to transfer skin into water droplet
4) Make sure skin is flat with no air bubbles
5) Put iodine drop on it
6) Place slide on arms of stage
cm -> mm -> µm -> nm
cm x10 mm x1000 µm x1000 nm
cm ÷10 mm ÷1000 µm ÷1000 nm
Magnification
Degree to which an image is made
Resolution
Smallest interval measurable between two points on an image
Nucleus
Controls all activities in the cell
Contains DNA
Cytoplasm
Where all chemical reactions take place
Holds everything together
Cell Membrane
Controls what goes in and out of the cell
Mitochondria
Releases energy
Aerobic respiration
Ribosomes
Makes protein for growth
Chloroplast
Contains chlorophyll for photosynthesis
Permanent Vacuole
Filled with cell sap
Supports cell and keeps it rigid
Cellulose Cell Wall
Strengthens cell
What eukaryotic cell doesn’t contain a nucleus
Red blood cell
Eukaryotic Cells
Animals
Plants
Fungi
Protista
Prokaryotic
Bacteria
Difference between eukaryotes and prokaryotes
- Prokaryotes are smaller
- Prokaryotes have no nucleus
- Prokaryotes contain plasmids
How are nerve cells adapted?
Fatty Sheath = insulate axon
Long axon = carry impulses long way
Lots of mitochondria = energy
How are muscle cells adapted?
Contain special proteins = making fibres contract
Mitochondria = energy for cells to contract and relax
Store glycogen = cellular respiration, energy for fibres to contract
How are sperm cells adapted?
Long tails = travel long distances
Mitochondria = energy for tail to work
Digestive enzymes = breaking down outer layer of egg
Nucleus = contains genetic information
What is meant by “specialised”?
Physical or chemical changes
Being suited to a specific purpose
How are root hair cells adapted?
Surface area = movement of water into cell
Large Permanent vacuole = speeds up osmosis
Mitochondria = transport energy needed for active transport
How are photosynthetic cells adapted?
Chloroplast = photosynthesis
Positioned into layers = absorb as much light as possible
Large permanent vacuole = keeps cell rigid
How are xylem cells adapted?
Cells die = form hollow tubes to allow water and mineral ions to move through them
Rings of lignin = strong to withstand pressure
How are Phloem cells adapted?
Sieve plates = carry dissolves food up and down tubes
Lose internal structures = supported by companion cells and move dissolves food
What is the definition of Diffusion?
The spreading out of particles in a solution or gas resulting in the net movement from an area of high concentration to an area of low concentration, down the concentration gradient
What are the two factors affecting diffusion?
Temperature
Concentration
How does concentration affect Diffusion?
If there’s a big concentration difference, diffusion is quick
If there’s a small concentration difference, diffusion is sow
Particles move towards area of low concentration
Difference between 2 areas is the concentration gradient
The bigger difference, the steeper the concentration gradient
Example of diffusion
Gas exchange: CO2 moves out from body cells into red blood cells. Then back into the air in the lungs by diffusion down the concentration gradient.
Osmosis definition
The movement of water from a dilute to a more concentrated solution through a partially permeable membrane that allows water to pass through
What does it mean if the solution is dilute or concentrated?
Dilute = high concentration of water, low concentration of sugar Concentrated = high concentration of sugar, low concentration of water
Isotonic
Internal and external concentration are the same
Hypertonic
Solution outside cell is higher than internal
Hypotonic
Solution outside cell is lower than the internal concentration
How does osmosis maintain the transport of water from a plant’s roots to leaves?
Water enters roots by osmosis
Water progresses from cell to cell
Water moves up the plant
Eventually reaches leaves or travels by xylem
What is meant by the term Turgid?
Plants surrounding fluid is hypotonic to cytoplasm
Has lower concentration of solutes and higher concentration of water
What is meant by the term Turgor?
Solution surrounding cell is hypertonic to cell
Water leaves
Wilts
What is meant by the term Plasmolysis?
Even more water leaves
Vacuole and cytoplasm shrink
Cell membrane pulls away from cell wall
Investigating osmosis in plants method
1) Prepare sugar solutions and select range you want to use to measure them.
2) Set up multiple boiling tubes with each of these solutions and one with distilled water for the controlled variable
3) Label each tube with its concentration
4) Draw a table before experiment
5) Weigh all of the potato’s masses before putting in cylinder and then again after
6) For each sugar concentration repeat the investigation with each potato cylinder
7) Calculate the mean using all experiments ignoring anomalies
8) If the sugar concentration is higher outside than inside the potato, it will weigh more, water will move in.
9) Take care with scalpel, wear eye protection when wearing chemical solutions, do not cut potato towards hands
Active transport definition
Moves substances from a more dilute solution to a more concentration solution
How does active transport use energy?
Uses energy released from food in respiration to provide the energy required
Describe how water moves from the soil to the leaf
Water moves into the roots via osmosis Water moves from the root hair cells into the xylem via osmosis Water moves up the plant via the xylem Evaporation of water from leaves Produces tension and pulls on the water This is the transpiration stream
What’s the difference between the Phloem and Xylem?
Xylem = transports water via transpiration Phloem = transports mineral ions and nitrates via translocation
Adaptations for increasing the rate of diffusion
Short diffusion distance
Big concentration difference
Large surface area
How are the lungs adapted for diffusion?
- (large surface area, alveoli, thin membrane, high diffusion rate, high gas exchange rate)
- Alveoli have a large surface area
- Capillaries are thin, one cell thick are close to the alveoli which provides short diffusion path for O2 and CO2
- Lungs are ventilated, bring in (fresh) oxygen and remove carbon dioxide, maintaining a concentration gradient
- Large capillary network (around alveoli) and good blood supply which removes oxygenated blood quickly
- Brings CO2 to the lungs quickly maintaining a concentration gradient
