Topic 4: Plant minerals theory and Core Practical Flashcards
How do plant mineral ions enter plants?
3 steps
- active transport (due to low mineral ion conc. in soil)
- using ATP and membrane protein
- into root hair cells
NOTE: in an exam, must say “inorganic ions” or “mineral ions”, not just “minerals”
How are plant mineral ions transported from roots to leaves?
1 way
- dissolved in water, in the xylem
What are the key functions of nitrate ions?
4 functions
- Makes amino acids, which make proteins for use as enzymes
- Makes ATP as energy source
- Makes organic, nitrogenous bases to make DNA + RNA
- Makes chlorophyll so light can be absorbed for photosynthesis
What are the symptoms of a nitrate ions deficiency?
3 symptoms
- {Slow/stunted} growth, so smaller plant
- Lack of side shoots (spindly plants)
- Older leaves turn yellow and die
What are the key functions of magnesium ions?
1 function
- Used to make chlorophyll, so light can be absorbed for photosynthesis
What are the symptoms of magnesium ions deficiency?
2 symptoms
- Yellow leaves as less green chlorophyll can be made
2. {Slow/stunted} growth as less photosynthesis
What are the key functions of calcium ions?
1 function
- Forms calcium pectate, with pectin, to form middle lamella which holds adjacent plant cells together.
What are the symptoms of calcium ions deficiency?
3 symptoms
- Young leaves turn yellow and crinkly
- Growing points die
- {Stunted/distorted} growth, as cells cannot hold together
(Core practical 7: plant mineral ion deficiencies)
Name the independent variable (1 point)
- Mineral ions solution with absence of one ion
(Core practical 7: plant mineral ion deficiencies)
How do you vary the independent variable?
(1 point)
- Use different mineral ion solutions with one mineral ion missing from each.
(Core practical 7: plant mineral ion deficiencies)
What is the experimental design focus? (1 point)
- Changing the concentration of one specific mineral ion
(Core practical 7: plant mineral ion deficiencies)
What is the negative control? (1 point)
Why? (2 points)
- Plant grown in distilled water - 0% concentration ions:
- For comparison.
- To determine the {growth/height/mass} in the absence of added mineral ions - to see that the {solvent/distilled water} used to make up the mineral ion solutions did not have an effect
(Core practical 7: plant mineral ion deficiencies)
What is the positive control? (1 point)
Why? (2 points)
- Plant grown in a solution with all mineral ions present in high enough concentrations for optimum plant growth requirements.
- For comparison
- To determine the {growth/height/mass} in with all mineral ion - {maximum/optimum} growth
(Core practical 7: plant mineral ion deficiencies)
Name the dependent variable (1 point)
- Plant growth
(Core practical 7: plant mineral ion deficiencies)
How is the dependent variable measured? (2 ways - quantitative)
What is a suitable time period? (1 point)
What needs to be calculated at the end? (1 point)
- Height of plant - from base of stem to top of stem with a ruler
- Mass of plant - with a top-pan balance
- 4 weeks
- % increase in {height/mass}
(Core practical 7: plant mineral ion deficiencies)
How is the dependent variable measured? (1 way - qualitative)
How is it recorded? (1 point)
- Observations (e.g. colour of leaves) - by comparing to colour chart
- By taking photos
(Core practical 7: plant mineral ion deficiencies)
What are the controlled organism variables (3 variables)
For each controlled variable, why is it controlled? (1 point)
- Same plant {species/variety} or genotype - use same parent plant OR use cloned seedlings so they are genetically identical.
WHY: Some plant seedlings may have alleles that give them the potential to be tall, while others may not, so using clones will allow the effect of the minerals to be seen. - Same age - germinated at same time
WHY: Seedlings of different ages may have different growth rates - Same germination/growing conditions prior to experiment - same experiment (incubator), light intensity (light bank) etc.
WHY: So they all have the same potential to be tall, and to allow the effects of the minerals to be seen.
(Core practical 7: plant mineral ion deficiencies)
What are the controlled environmental variables (3 variables)
For each controlled variable, why is it controlled? (1 point)
- Same light intensity - place tubes under a light bank
WHY: The higher the light intensity the higher the rate of photosynthesis and growth until light intensity becomes a limiting factor. - Same temperature - use heat shield/incubator
WHY: High temperatures could denature enzyme active sites and reduce rate of plant growth (height). Temperature affects plant growth as it affects the rate of photosynthesis and enzyme activity. - Same wavelength of light - use a white light
WHY: Blue/red light gives a higher rate of photosynthesis than other colours e.g. green which is reflected. Higher rate of photosynthesis, taller plants will grow.
(Core practical 7: plant mineral ion deficiencies)
What are the controlled procedural/method variables (3 variables)
For each controlled variable, why is it controlled? (1 point)
- Same growing time - 4 weeks
WHY: Longer times will allow more time for growth, so plants may grow taller/have greater mass - Same initial volume of mineral ion solution - use measuring cylinder or pipette.
WHY: Greater volumes will contain more mineral ions - Same concentration of any other mineral ions in solution - make up solutions with all mineral ions present in optimum concentrations
WHY: To be sure that it is the absence of the chosen mineral ion which is having an effect and not another mineral ion
(Core practical 7: plant mineral ion deficiencies)
Use _____ instead of soil, as soil contains mineral ions - we don’t know which ones and in what concentration
Perlite
(Core practical 7: plant mineral ion deficiencies)
What should be repeated and how many times? (1 point)
Why? (3 points)
- Repeat 5 times for each mineral ion solution
Why:
- To identify, discard and repeat anomalies to obtain 3 concordant results
- To calculate a mean
- To improve reliability
(Core practical 7: plant mineral ion deficiencies)
What needs to be done for reliability? (1 point)
Carry out 5 repeats for each mineral ion solution
(Core practical 7: plant mineral ion deficiencies)
What needs to be done for validity? (4 points)
- 5 different values for independent variable (5 data points on graph allow trend to be established)
- The more values you add in between/more points on the graphs between the extremes, the greater the validity
- controlled variables (to confirm that the dependent variable is being affected by the independent variable being investigated rather than some other variable - data and conclusions drawn from it are more valid)
- A control (for comparison)
(Core practical 7: plant mineral ion deficiencies)
Key Summary: What is the method for this practical?
(6 points)
- Add 10 cm3 of each mineral ion solution to perlite in boiling tubes - no nitrogen, no magnesium, no calcium) + distilled water + solution with all mineral ions as controls
- Place a sprouting mung bean/plant seedling onto Perlite
using sterile forceps - Cover with cling-film and place under a light bank
- Controlled variables to increase validity – seedlings same
age, clones, variety/species, same temperature using a
heat shield, same volume of mineral solution using pipette,
same light intensity - Measure height/mass each day for 4 weeks
- Repeat 5 times for each mineral solution so anomalies
can be identified, 3 concordant results obtained and mean
height calculated to increase reliability
(Core practical 7: plant mineral ion deficiencies)
What is the equipment needed for the practical?
9 things
- Boiling tubes
- Perlite
- Ruler
- {top-pan/mass balance}
- Graduated pipette
- Light bank
- Thermometer
- Incubator
- Mineral ion solutions (not nutrient broth or agar)
(Core practical 7: plant mineral ion deficiencies)
Half fill five tubes with Perlite granules (not soil)
What is the purpose of this step? (2 points)
- Granules support the seedling roots as it grows
2. Soil cannot be used as it contains mineral ions
(Core practical 7: plant mineral ion deficiencies)
Add 10cm^3 of mineral solution to each of 3 tubes (tube 1 = no nitrogen, tube 2 = no magnesium, tube 3 = no calcium)
What is the purpose of this step? (1 point)
- To investigate the effect of deficiency of each mineral
(Core practical 7: plant mineral ion deficiencies)
Add 10cm^3 of water to tube 4 and all mineral solutions to tube 5
What is the purpose of this step? (2 points)
- As controls
2. Plant growth/height for other tubes can be compared with them
(Core practical 7: plant mineral ion deficiencies)
Place a mung bean seedling into the Perlite using sterile forceps (roots pointing downwards)
What is the purpose of this step? (1 point)
- Forceps keep tubes sterile and prevent bacterial contamination which may reduce growth through competition for minerals.
(Core practical 7: plant mineral ion deficiencies)
Cover tubes with cling-film (rather than metal lid)
What is the purpose of this step? (1 point)
- Allows light to reach plant seedling in tube
(Core practical 7: plant mineral ion deficiencies)
Place tubes under a light bank
What is the purpose of this step? (1 point)
- Light is required for photosynthesis, for growth.
(Core practical 7: plant mineral ion deficiencies)
Measure {height/mass/number of leaves} and assess health (photos) each day for 4 weeks
What is the purpose of this step? (2 points)
- As a measure of growth/health
2. To assess how the mineral deficiency has affected the plant
(Core practical 7: plant mineral ion deficiencies)
Add the same volume of the correct solution to each tube on a regular basis
What is the purpose of this step? (2 points)
- To have the same mineral concentration for all tubes (except for the one missing minerals)
- To supply water
(Core practical 7: plant mineral ion deficiencies)
Repeat the practical 5 times for each mineral solution
What is the purpose of this step? (1 point)
- To identify anomalous results, obtain 3 concordant results and calculate a mean {height/mass/number of leaves}, to improve liability.
List the experimental design checklist
9 things
- IV – independent variable + how varied? (validity)
- C – control (validity)
- M – key method steps
- CVO – controlled variables for plants (validity)
- CVE – controlled variables for environment (validity)
- CVP – controlled variables for procedure/method (validity)
- R – repeats – how many, what and why? (reliability)
- S – safety (if relevant)
- E – ethical issues (if relevant)
