6 (plant structures + functions) - exam qs

• Suggest reasons why there are more stems with five or more flowers in the open grassland.

  They can photosynthesise more as there is a higher light intensity and there is more rain.
• Through what process does carbon dioxide enter leaves?

  Diffusion
• Explain how changes to the guard cells on a warm day help the plant to survive:

  The guard cells close stomata to reduce water loss or so that the rate of transpiration is reduced
• Which cell will make the most glucose in leaves?

  Palisade cells, cell B

  
• Describe how carbon dioxide enters the leaf.

  Diffusion from an area of high concentration to an area of low concentration through the stomata.
• Describe the process that takes place in the leaf to produce oxygen.

  Chloroplasts contain chlorophyll. Chlorophyll is a green pigment that absorbs sunlight. Chloroplasts are the site of photosynthesis and it requires carbon dioxide and it produces oxygen and water.
• What is the process by which water entered the root hair cell?

  Osmosis
• What is the process by which mineral ions enter the root hair cell?

  Active transport
• Suggest a benefit to a plant of being day neutral:

  Plant can flower all year round
• What is photoperiodism?

  Plants flowering in response to the number of hours of darkness and light
• The leaves of some species of bamboo plants contain the poison cyanide. Suggest how these bamboo plants benefit from having poisonous leaves.

  They are less likely to be eaten by animals
• The greater bamboo lemur is adapted to tolerate cyanide. This means that it can eat bamboo leaves containing cyanide. Explain how the co-evolution of bamboo plants and the greater bamboo lemur could have occurred.


  The bamboo plants that produce cyanide survived to reproduce and mutation in greater bamboo lemur allowed them to tolerate cyanide
• What would be the ideal features of compost for strawberry plants during a hot summer?

  Moisture retention and nutrient - rich.
• Why would reducing the water content in strawberries help preserve them?

  It reduces the number of microorganisms that can reproduce therefore reducing the decay process and preserving the food.
• Give a method of measuring light intensity:

  Use a lux meter, calculate it
• How can you measure the volume of gas released accurately?

  Collect the gas/oxygen produced in a graduated gas syringe to reduce the errors generated when counting bubbles that could be of different sizes
• What is the process that resulted in the type of root growth shown in photograph B?

  Positive gravitropism

  
• How does growth (due to positive gravitropism) occur?

  Auxin moves to the underside of the plant root. It inhibits the elongation of root cells and the cells on the upper side continue to elongate. This makes the root grow downwards towards gravity.
• What are the advantages to the plant of this negative gravitropism response?

  It anchors the plant to make it stable. The roots can reach water and absorb water and mineral ions
• Why did Rebecca and Andrew set up a control experiment?

  So that you have something to compare the experimental results to

  
• Explain the results of Rebecca's experiment and Andrew's experiment:

  Rebecca's shoot didn't curve because the black cap does not allow light to shine on the tip meaning auxin will not move to that side of the shoot and is instead evenly distributed. Andrew's shoot did curve because the jelly will allow the auxin to diffuse through to the shaded side causing cell elongation.

  
• What is the plant hormone that causes the cress seedlings to grow towards the light?

  Auxin
• The student had two growing plant shoots and placed them both in a window with light coming from one direction. Describe a method the student could use to show that the hormone was found in the tip of the plant shoot.

  Remove the tip of one plant shoot and compare the differences in their growth or responses.
• Why is the waxy cuticle important for this pine leaf?

  It surrounds the pine leaf preventing water loss (prevents dehydration)

  
• How does sucrose move through the plant?

  Translocation is the transport of sucrose through the phloem in a plant
• Explain how auxins cause the shot of a plant to grow towards the light:

  Auxins move to the shaded side of a shoot causing cells on the shaded side to elongate
• Fruit ripening is one use of plant hormones. Describe how it is used in selective weedkillers.

  They can be used in selective weedkillers which allows broad leaved plants to grow uncontrollably and die but narrower leaved plants and crops left unaffected. Auxins and Gibberellins are used
• Fruit ripening is one use of plant hormones. Describe how it is used in rooting powders.

  Plant cuttings are dipped into rooting powder and roots develop rapidly. A large number of plants can be produced from the same plant and there is no need to wait for plants to grow from seeds. Auxins are used.
• Fruit ripening is one use of plant hormones. Describe how it is used in seedless fruit production.

  The fruits will develop but the seeds inside won't meaning the fruits can grow larger (they have a larger biomass). Gibberellins are used.
• Explain how water moves from cell to cell in a leaf:

  By osmosis - water moves from an area of high water concentration to an area of low water concentration through a partially permeable membrane
• Some small plants can grow on the bark of trees. The distribution of two plant species, species A and species B, growing on the north and south sides of a tree was investigated. Suggest reasons for the distribution of species B on the north and south sides of the tree.

  Species B can grow on both the North and South sides but there are more on the South side because of a specific difference in a named abiotic factor like it may be lighter or darker. There are fewer on the north side because they are out competed by species A.