PLANT NUTRITION Flashcards
Name few inorganic substances…
Carbon dioxide, water, minerals (from air soil)
define photosynthesis
The process by which plants manufacture carbohydrates from raw materials using the energy from sunlight.
Balanced equation of photosynthesis
6CO2+6H2O —energy from sunlight–> C6H12O2+ 6O2
Describe chlorophyll and explain its function
It is a green pigment found in chloroplasts that absorbs energy from sunlight to drive photosynthesis.
Balanced equation of respiration
C6H12O2+6O2—light energy–> 6CO2+ 6H2O (Opposite of the process of photosynthesis)
Why is glucose not good for storage in a leaf?
It is soluble, and it is reactive
What is glucose converted into for storage? And where is it stored?
It is converted into starch and can be stored inside the chloroplasts.
State the uses of glucose
It is used to make amino acids
It is used to build fats and oils
It is used in respiration (to build smaller molecules into bigger ones).
Why is nitrogen needed in plants?
To make proteins, hence for growth
Why is magnesium needed in plants?
To make chlorophyll
Symptoms of nitrogen deficiency in plants are-
Stunted growth, yellowing leaves
Symptoms of magnesium deficiency in plants are-
yellowing between the veins of the leaves
What is glucose changed into for transportation?
It is changed into sucrose
The function of phloem tubes
It takes away sucrose and amino acids to parts of the plant TRANSLOCATION
The function of xylem vessels
It supplies H2O and mineral ions to the cells of the leaf, aiding photosynthesis TRANSPIRATION
Why is the leaf supported by the stem and petiole?
To expose as much of the leaf as possible to sunlight and air
Name 5 ways in which the leaf is adapted
Large surface area- To expose as large an area as possible to the sunlight & air.
Thin- Sunlight can reach all the cells & to let carbon dioxide & oxygen diffuse faster
Air spaces in spongy mesophyll cells- To allow CO2 & O2 to diffuse in and out of the cells
Xylem vessels and Phloem vessels within a short distance of every mesophyll cell
What % of air is carbon dioxide?
0.04%
How does CO2 get into a leaf?
By diffusion through the stoma
What is used as energy in plants?
Glucose
Why do plants photosynthesize?
Plants are autotrophs, they need to make their own food, they make glucose for energy.
Why do plants need water?
It is an essential raw material for photosynthesis
It supports and cools the plants.
It carries mineral ions (nutrients) from the roots to the leaf.
Why is glucose changed to starch immediately
It will draw water, by osmosis
Name some plant cells without chloroplasts
Root hair cells
Epidermal cells (Upper and lower)
Xylem and Phloem vessels
Describe an experiment to show that chlorophyll is essential for photosynthesis
Test a variegated leaf for the presence of starch; using iodine solution; Destarch the leaves; Expose the leaf to sunlight for a few days; test the leaf for starch; Only the green parts of the leaf will turn blue-black.
Describe an experiment to show that light is essential for photosynthesis
Destrach a leaf; Do the starch test to make sure no starch is present; cover a part of the leaf with thick black paper; place the plant in sunlight for few days. Remove the strip and test the leaf for starch.
Describe an experiment to test a leaf for starch
-A variegated leaf is dropped in boiling water to kill and break down the cell walls
The leaf is left for 5-10 minutes in hot ethanol in a boiling tube. This removes the chlorophyll so color changes from iodine can be seen more clearly
The leaf is dipped in boiling water to soften it
The leaf is spread out on a white tile and covered with iodine solution
In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
-The white areas of the leaf contain no chlorophyll and when the leaf is tested only the areas that contain chlorophyll stain blue-black
The areas that had no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored
Test for carbondioxide
Place a test plant in a container with a carbon dioxide absorber (i.e. sodium hydroxide) and a control plant without the absorber. The absorber will remove the carbon dioxide.
A starch test is then carried out after several hours. The results should show that the test plant has a negative result whereas the control plant has a positive one.
Explain why chlorophyll is removed from the leaf before testing it for starch.
Chlorophyll conceals the color change (shown with iodine) as it is a green pigment.
Plant B was used as a control in the experiment. Explain the importance of this control.
To show that the factor under test is responsible for the change observed
Explain why the plant was destarched
To be sure that starch is produced during the experiment
Define limiting factor
Something present in the environment in such short supply that it restricts life processes.
Three adaptation or structure of the xylem vessel
Hollow long
no cell contents
Lignified walls
