PLANT NUTRITION

Question 1

Name few inorganic substances…

Answer 1

Carbon dioxide, water, minerals (from air soil)

Question 2

define photosynthesis

Answer 2

The process by which plants manufacture carbohydrates from raw materials using the energy from sunlight.

Question 3

Balanced equation of photosynthesis

Answer 3

6CO2+6H2O —energy from sunlight–> C6H12O2+ 6O2

Question 4

Describe chlorophyll and explain its function

Answer 4

It is a green pigment found in chloroplasts that absorbs energy from sunlight to drive photosynthesis.

Question 5

Balanced equation of respiration

Answer 5

C6H12O2+6O2—light energy–> 6CO2+ 6H2O (Opposite of the process of photosynthesis)

Question 6

Why is glucose not good for storage in a leaf?

Answer 6

It is soluble, and it is reactive

Question 7

What is glucose converted into for storage? And where is it stored?

Answer 7

It is converted into starch and can be stored inside the chloroplasts.

Question 8

State the uses of glucose

Answer 8

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).

Question 9

Why is nitrogen needed in plants?

Answer 9

To make proteins, hence for growth

Question 10

Why is magnesium needed in plants?

Answer 10

To make chlorophyll

Question 11

Symptoms of nitrogen deficiency in plants are-

Answer 11

Stunted growth, yellowing leaves

Question 12

Symptoms of magnesium deficiency in plants are-

Answer 12

yellowing between the veins of the leaves

Question 13

What is glucose changed into for transportation?

Answer 13

It is changed into sucrose

Question 14

The function of phloem tubes

Answer 14

It takes away sucrose and amino acids to parts of the plant TRANSLOCATION

Question 15

The function of xylem vessels

Answer 15

It supplies H2O and mineral ions to the cells of the leaf, aiding photosynthesis TRANSPIRATION

Question 16

Why is the leaf supported by the stem and petiole?

Answer 16

To expose as much of the leaf as possible to sunlight and air

Question 17

Name 5 ways in which the leaf is adapted

Answer 17

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

Question 18

What % of air is carbon dioxide?

Answer 18

0.04%

Question 19

How does CO2 get into a leaf?

Answer 19

By diffusion through the stoma

Question 20

What is used as energy in plants?

Answer 20

Glucose

Question 21

Why do plants photosynthesize?

Answer 21

Plants are autotrophs, they need to make their own food, they make glucose for energy.

Question 22

Why do plants need water?

Answer 22

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.

Question 23

Why is glucose changed to starch immediately

Answer 23

It will draw water, by osmosis

Question 24

Name some plant cells without chloroplasts

Answer 24

Root hair cells
Epidermal cells (Upper and lower)
Xylem and Phloem vessels

Question 25

Describe an experiment to show that chlorophyll is essential for photosynthesis

Answer 25

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.

Question 26

Describe an experiment to show that light is essential for photosynthesis

Answer 26

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.

Question 27

Describe an experiment to test a leaf for starch

Answer 27

-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

Question 28

Test for carbondioxide

Answer 28

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.

Question 29

Explain why chlorophyll is removed from the leaf before testing it for starch.

Answer 29

Chlorophyll conceals the color change (shown with iodine) as it is a green pigment.

Question 30

Plant B was used as a control in the experiment. Explain the importance of this control.

Answer 30

To show that the factor under test is responsible for the change observed

Question 31

Explain why the plant was destarched

Answer 31

To be sure that starch is produced during the experiment

Question 32

Define limiting factor

Answer 32

Something present in the environment in such short supply that it restricts life processes.

Question 33

Three adaptation or structure of the xylem vessel

Answer 33

Hollow long
no cell contents
Lignified walls