Chapter 6: PLant Nutrition

Question 1

Photosynthesis

Answer 1

the process by which plants synthesise carbohydrates and other raw materials using energy from light.

Question 2

Chlorophyll

Answer 2

the chlorophyll of the plant’s leaves, water and carbon dioxide react together to make carbohydrates and oxygen.
Chlorophyll is able to capture energy from sunlight. When it has done this it immediately passes the energy on (transfers it) to water molecules and carbon dioxide molecules. The energy makes the substances react producing a kind of carbohydrate called glucose.

Question 3

formula of photosynthesis

Answer 3

6C02 + 6H2O –> C6H12O6 + 6O2
Like all organisms, photosynthesis requires enzymes to help it take place.

Question 4

What happens to the two products of photosynthesis?

Answer 4

Oxygen is released into the atmosphere or into the water if the plant is aquatic.
Glucose is used for many different purposes.

Question 4

releasing useful energy

Answer 4

glucose is used to provide energy for various activities that the cells have to undertake. For example, energy is needed to move the mineral ions into the rot hair cells by active transport or for building protein molecules from amino acids for growth.

Question 5

storing for use later

Answer 5

Pants usually make more glucose than they need to use for energy later. they store this as starch.

Question 6

how are starch molecules made?

Answer 6

They are made by linking many molecules together to make a long spiral chain. Millions of these molecules come together to (clump) to make a starch grain.

Question 7

Starch grains

Answer 7

they are not soluble in water so they do not get involved in chemical reactions taking place inside the plant cells.
They also do not affect the concentration of solutions inside the cell so they do not cause water to enter or leave by osmosis.
the starch molecules can easily be broken down into glucose molecules went the plant needs them.

Question 8

making sucrose for transport

Answer 8

Plants can only make glucose in parts where chlorophyll is present which is the leaves.
And so in order to transport the glucose to other parts of the plant, glucose is changed into a sugar with larger molecules called sucrose.
The sucrose is carried from one part of the plant to another inside tubes called phloem tubes.

Question 9

sucrose

Answer 9

a sugar whole molecule is made of glucose and another similar molecule (fructose) liked together.

Question 10

making cellulose

Answer 10

Cellulose is required to make new cell walls for new cells.
Cellulose is made of linking long chains to stay straight rather than coil in spirals like starch is made.

Question 11

Making nectar

Answer 11

Many plants reproduce sexually making male and female gametes in flowers. unlike animal gametes, male gametes cannot move from place to place so the pant relies on insects, bats or birds to carry them, inside pollen grains from one flower to another.
Flowers produce nectar that animals can feed on.

Question 12

Nectar

Answer 12

a sweet liquid secreted by many insects pollinated flowers to attract their pollinators.

Question 13

making amino acids

Answer 13

Glocuse is used to make amino acids which in is turn used to make proteins for growth.
Proteins contain carbon, hydrogen, oxygen and nitrogen. The source of nitrogen the plants get is present in the soil in the form of nitrate ions.
These ions are taken up by active transport through the root hairs where they are transported to all parts of the pant to be combined with glucose to make amino acids.
Without nitrates ions, the pant cannot synthesise proteins and therefore be unable to grow quickly or strongly.

Question 14

Chlorophyll

Answer 14

Glucose is used to make chlorophyll.
Chlorophyll is not a protein but it contains nitrogen and magnesium. Without magnesium ions, the leaves will start to look yellow rather than green. If a pant cannot make enough chlorophyll it will not photosynthesis well and therefore will not grow well.

Question 15

nitrates

Answer 15

nitrogen
used to make amino acids for proteins that are used for plant growth.

Question 16

phosphates

Answer 16

phosphorous
for proteins, respiration and growth used for making DNA and RNA and cell membranes.

Question 17

potassium compounds

Answer 17

for respirations and photosynthesis, needed for enzymes involved in respiration and photosynthesis

Question 18

magnesium compounds

Answer 18

for photosynthesis and making of chlorophyll.

Question 19

NPK values

Answer 19

shows the relative portion of N, P, and K present in the fertiliser which helps farmers choose the right fertilizer as per the soil conditions in their fields.
Plants like tomatoes do need soil to grow - hydroponic.

Question 20

what is mineral deficiency?

Answer 20

is when the plant lacks enough of the mineral from the soil hence decreasing their healthy growth.

Question 21

mg deficiency

Answer 21

yellow leaves

Question 22

ph deficiency

Answer 22

poor growth of roots, discoloured leaves

Question 23

PO deficiency

Answer 23

poor growth of fruits, flowers, discoloured leaves

Question 24

N deficiency

Answer 24

yellow leaves, poor, growth

Question 25

structure of the leaf

Answer 25

a leaf consists of a broad flat part which is joined to the rest of the plant by a leaf stalk.
Inside the stalk area collections of parallel tubes called vascular bundles also form the veins of the leaf.
The tubes in the vascular bundles carry substances to and from the leaf.

Question 26

Chrlophyll leaf

Answer 26

Chlorophyll is found in chloroplasts that are present in the leaf cells. Chlorophyll is spread out on membranes so that a lot of sunlight can reach it. And also so it can also capture light from different parts of the sun’s spectrum.

Question 27

vascular bundles

Answer 27

collections of xylem tubes and phloem vessels running side by side which form veins of the leaves.

Question 28

Adaptations of leaves

Answer 28

Most leaves have a large surface area and are very thin.
A very large surface area allows large amounts of sunlight to fall onto the leaf. The large surface area also increases the rate at which carbon dioxide can diffuse into the leaf from the air.
The sunlight can pass right through the leaf allowing many leaves to photosynthesis and the thinness also helps CO2 to reach all the cells quickly by diffusion

Question 29

upper epidermis

Answer 29

Cells and packed tightly together to reduce the quantity of water vapour from escaping from the leaf.
They do not contain chloroplasts so they cannot photosynthesis.
The cells secrete a waxy instance which forms a thin, transparent, waterproof layer called the cuticle.

Question 30

palisade mesophyll layer

Answer 30

Below the upper epidermal layer.
Made up of tall narrow cells containing a very large number of chloroplasts.
Their main function is photosynthesis.
As they are close to the top of the leaf they get plenty of sunlight. The transparent epidermis cells above them let the light through easily.

Question 31

Spongy mesophyll layer

Answer 31

Below the palisade mesophyll layer.
The cells in this tissue also contain chloroplasts but as many in the palisade mesophyll cells.
They are not as tightly packed either.
There are many airspaces between them that allow carbon dioxide and oxygen to diffuse between the air and the cells inside the leaf.
The spaces also allow vapour to move from the surface of the cells to the outside of the leaf.
Allows for very large internal structure to surface area.

Question 32

lower epidermis

Answer 32

the bottom of the leaf is covered in a tissue similar to eh upper epidermis.
on some leaves, the cuticle is present, although it is not required.
as the underside of the leaf does not have sunlight falling on it does not get as hot and therefore does not lose as much water vapour.
There are openings called stomata, each stoma is surrounded by a pair of guard cells (they do not have any chloroplasts).
The guard cells change their shape which can open and close the stoma.
The stomata allow for the diffusion of carbon dioxide and oxygen in and out of the leaf.
Water vapour also diffuses out the leaf through the stomata.

Question 33

stomata

Answer 33

openings in the surface of the leaf most commonly on the lower surface; they are surrounded by pairs of guard cells which control whether the stomata are open or closed.

Question 34

guard cells

Answer 34

a pair of cells that surrounds a stoma and controls its opening; guard cells are the only cells in the epidermis that contain chloroplasts.

Question 35

hydrogen carbonate indicator

Answer 35

purple - no CO2
red- little CO2 (ordinary air)
yellow- a lot of carbon dioxide

Question 36

limiting factor

Answer 36

a factor that is in short supply which stops an activity such as photosynthesis from happening at a faster rate.

Question 37

stomata limiting factor

Answer 37

-Stomata often close when the weather is hot and that prevents too much water from being lost.
This means that on a really hot or bright day, photosynthesis may slow down.

Question 38

imp statement for limiting factor graphs

Answer 38

The rate of photosynthesis increases linearly as the concentration of CO2/ intensity of light increases until a certain point at which the factor is no longer a limiting factor and hence the rate falls into a constant.

Question 39

experiment on testing for starch

Answer 39

-Fill a beaker with water and boil it. Place the leaf in the water using forceps for 1 to 2 minutes.
(this denatures the enzymes and stops chemical reactions).
-Put the leaf into a boiling tube and pour enough ethanol to fully immerse/ submerge the leaf.
-Place the boiling tube into a beaker of boiling water.
(A water bath is used to prevent any fire hazards from occurring due to ethanol being flammable).
-Remove the heat when the alcohol boils.
-Re-introduce the flame when ethanol stops boiling. Repeat until the leaf is completely discoloured.
(When chlorophyll has been removed (leaf looks while) remove the leaf from ethanol (the leaf is brittle). (Ethanol extracts water from the leaf).
-Dip the leaf into the water to soften it and make it permeable.
-Using a pipette add iodine solution to the leaf structure. A blue-black indicated that starch is present.

Ethanol is green in colour due to the green pigment chlorophyll leaving the leaf and getting suspended in the ethanol.
-Blue-black when iodine is added to the leaf.
-It shows that starch is present in leaves (depending on the amount of light, the increase of starch changes).

Question 40

Experiment 2: to show CO2 is necessary for photosynthesis

Answer 40

Set up the experiment as shown above and exposed to light for 2-6 hours. Obtain a leaf and test for starch.

Question 41

experiment 3: to show chlorophyll is present

Answer 41

leaf plant for 2-6 hours in the light.
Remove one leaf and show the green and non-green parts of the leaves
-Test leaf for starch.

Question 42

Experiment 4: Showing that oxygen is given during photosynthesis

Answer 42

Set up the experiment as shown. Expose it to light for 2 hours. The gas relights the glowing splint when in the presence of oxygen or makes it glow brighter.