Section 1 - Structures and Functions Flashcards Preview

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Flashcards in Section 1 - Structures and Functions Deck (34)
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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