Unit 1 Flashcards
Explain how cellulose molecules are adapted for their function in plant cells (3)
- Long and straight chains
- Become linked by hydrogen bonds to form fibrils
- Provide strength to cell walls
Cotton is a plant fibre used to make cloth. Explain how cellulose gives cotton its strength (3)
Long, straight chains form microfibrils and are held together by hydrogen bonds
“Push down hard on the coverslip, but do not push the cover sideways” Explain why (2)
- push hard to squish tissue
- don’t push sideways to avoid rolling the cells together
Describe how a saturated fatty acid differs to a molecular structure from an unsaturated fatty acid (2)
- Saturated fatty acids don’t have a double bond in the hydrocarbon chain
- Cannot accept more hydrogen
Name the type of bond between a Glycerol molecule and a fatty acid (1)
- Ester bond
Explain why a buffer solution was added to the amylase-starch mixture (2)
- to keep pH constant
- A change in pH may denature amylase
Contrast the processes of facilitated diffusion and active transport (3)
- Active transport requires ATP, facilitated diffusion doesn’t.
- Facilitated diffusion involves channel or carrier proteins, Active transport only involves carrier proteins.
- FD goes down C.D., AT goes against.
Describe the structure of a cellulose molecule and explain how cellulose is adapted for its functions in cells (6)
- made up from B-glucose
- joined by condensation to form a 1-4 glycosidic bond
- hydrogen bonds link chains
- cellulose makes cell walls strong
- can resist osmotic pressure as the bond is difficult to break
Describe two ways in which molecules of cellulose are similar to molecules of starch (2)
- They’re both polymers joined by condensation to form 1-4 glycosidic bonds.
- Both made up of glucose
Explain one way in which starch molecules are adapted for their function in plant cells (2)
- Starch has a helical structure so it is compact and can store a lot of energy in a small space
Mucus contains protein. Name one organelle that you would expect to find in large numbers in a mucus-secreting cell and describe its role in the production of mucus (2)
- Rough E.R.
- Produces Proteins
One theory of translocation states that organic substances are pushed from a high pressure in the leaves to a lower pressure in the roots. Describe how a high pressure is produced in the leaves (3)
- Water potential becomes lower as sugar enters the phloem
- Water enters phloem by osmosis
- Increased volume of water causes increased pressure
