Section 1 - Structures and Functions Flashcards
What are the seven life processes? [7 marks]
M ovement
R espiration
S ensititity
N utriton
E xcretion
R eproduction
G rowth
Key features of a plant and an example {5 marks}
- Multicellular
- They can photosynthesise (becuase they have chloroplasts)
- Their cells have cell walls, made of cellulose
- Plants store carbs as sucrose or starch
- E.g maize
Label this plant cell? [7 marks]
Key features of an animal and an example {7 marks}
- Multicellular
- Can’t photosynthesise (don’t have chloroplasts)
- Cells don’t have cell walls
- Most have some kind of nervous coordination
- Usually can move
- Often store carbs as glycogen
- E.g insects
Label this animal cell? [4 marks]
What is the difference between the cell walls of a plant cell and a fungi cell? [1 mark]
- Fungi cell walls are made of out chitin
- Plant cell walls are made of cellulose
Structure, photosyen, cell wall, feed, carbs, e.g
Key features of a fungi and an example {6 marks}
- Some are single-celled, others have a body called a mycelium, made up of hyphae
- Can’t photosyenthesise
- Cells have cell walls made of chitin
- Most feed by saprotrophic nutrition
- Can store carbs as glycogen
- E.g yeast
Can fungi photosyenthsise and how do they store carbs (2)
- Can’t photosyenthesise
- Store carbs as glycogen
Key features of a protoctists and an example {4 marks}
- Single celled and microscopic
- Some have chloroplasts (similar to plant cells)
- Some are more like animal cells
- E.g amoeba
Structure, nucleus, DNA, plasmids, photosyenthesise, feed, e.g
Key features of a bacteria and an example {7 marks}
- Single celled and microscopic
- Don’t have a nucleas
- Have a ciruclar chromosome of DNA
- Contain plasmids
- Some can photosyenthesise
- Most bacteria feed off other organisms (living and dead)
- E.g lactobacillus
Do bacteria have a nucleas and can they photosyenthesise (2)
- No
- Some can
structure, reproduction, infect, shapes, structure, e.g
Key features of viruses and an example {6 marks}
- Viruses are particles, not cells
- Only reproduce inside living cells (a parasite)
- They infect all types of living organsims
- Come in different shapes and sizes
- No cellular structure : have a protein coat around some genetic material
- E.g HIV
How can viruses reproduce (2)
- Only inside other living cells
- Viruses are parasites as they rely on other organisms
What are pathogens {3 marks}
- Organisms that cause disease
- Include some fungi, protoctists, bacteria and viruses
- E.g Viruses : Influenza virus
What is a catalyst? {2 marks}
- A catalyst is a substance which increases the speed of a reaction
- Without being changed or used up in the reaction
What is an enzyme {3 marks}
- Enzymes are biological catalysts
- Enzymes usually denature above about 45ºC
- They are proteins, made up of chains of amino acids
What is a substrate {1 mark}
- A molecule that is changed in a reaction
What is the ‘lock and key model’ {2 marks}
- An active site is the part where a substrate joins onto the enzyme
- A substrate is a molecule that is changed in a reaction
Explain this diagram {5 marks}
- Higher temperature increases rate of reaction
- Because of a higher collision rate
- If it gets too hot, some of the bonds holding the enzyme together will break
- Active site and subrstate won’t fit together, won’t form lock and key model
- Enzyme is denatured (optimum is 37 degrees)
Describe how to investigate the effect of temperature on enzyme activity {5 marks}
- The enzyme catalase catalyses the breakdown of hydrogen peroxide into water and oxygen
Catalase found in potatoes.
- Set the water bath to 10 degrees, and collect the oxygen produced in one minute using a measuring cyclinder.
- Set the water bath to different temperatures to see how temperature affects catalase
- Control variables such as enzyme conc and pH
How does pH affect enzyme activity {3 marks}
- If the pH is too high/low, the pH interferes with the bonds holding the enzyme together
- Most enzymes optimum pH is neutral, pH 7
- However, pepsin breaks down proteins in the stomach, pH 2
Define diffusion {2 marks}
- The net movement of particles from an area of high conc to an area of low conc
- Down the conc gradient
How do cell membranes use diffusion {3 marks}
- They hold the cell together; but let substances in and out as well
- Only very small molecules can diffuse through the cell membrane, e.g glucose, amino acids, oxygen
- Big molecules, e.g starch and proteins can’t fit through the membrane
Define osmosis {3 marks}
- The net movement of water molecules across a partially permeable membrane
- From a region of high to low water concentration
- Down the conc gradient
How are plants supported by turgid cells {4 marks}
- When a plant is well watered, all its cells draw water in by osmosis and become plump and swollen (turgid)
- Contents of the cell walll push against the cell wall (turgor pressure) which supports the plant tissues
- When there’s no water in soil, plants lose turgor pressure and wilt (flaccid)
- The plant doesn’t completly lose its shape, an inelastic cell wall keeps it in position
Describe how a student would investigate diffusion in a non-living system {6 marks}
- Use phenolphthalein, a pH indicator which is pink in alkaline solutions and colourless in acidic solutions
- Use to investigate diffusion in agar jelly
- Mix phenolphthalein, agar jelly and dilute sodium hydroxide (goes pink)
- Fill a beaker with some dilute HCL. Cut out a few cubes from the jelly and put themin the HCL
- Leave for a day
- Cubes eventually turn colourless, as acid diffuses into the agar jelly and neutralises the sodium hydroxide
Describe a way to investigate osmosis in living systems {6 marks}
- Cut a potato into identical cyclinders
- Fill one beaker with pure water, another with very concentrated sugar solution
- Put equal amount of potato cyclinders in each
- Measure length before, leave for 30 minutes, and measure lengths again
- If the cyclinder has drawn in water by osmosis, it will be longer, vice versa
- Repeat, take average, draw a graph
What is active transport {3 marks}
- Movement of particles against a conc gradient
- From an area of low conc to an area of high conc
- Using energy released during respiration
Explain how active transport is used in the digestive sstem {4 marks}
- Low conc of nutrients in the gut, but a high conc of nutrients in the blood
- Active transport allows nutrients to be taken into the blood, against the conc gradient
- Essential to stop starving
- However, active transport needs energy from respiration to make it work
Name the 3 main factors which affect the movement of substances {3 marks}
- Surface area to volume ratio
- Temperature
- Conc gradient
How does surface area to volume ratio affect rates of diffusion, osmosis and active transport {2 marks}
- Rate of diffusion, osmosis, active transport is higher in cells with a higher surface area to volume ratio
- Larger surface area to volume ratio means substances can move into and out of the cell faster
How does temperature affect rates of diffusion, osmosis and active transport {2 marks}
- As particles get warmer, they have more energy, meaning they move faster
- As temperature increases, substances move in and out of cells faster
How does the conc gradient affect rates of diffusion, osmosis and active transport (2)
- Substances move in and out of cells faster if there is a big difference in conc, inside and out of the cell
- Only increases the rate of diffusion and osmosis, conc gradients don’t affect the rate of active transport
