B4 Plant nutrition

Question 1

What is nutrition?

Answer 1

Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient nutrients causes malnutrition.

Question 2

What is metabolism?

Answer 2

Metabolism is the process by which your body converts what you eat and drink into energy. During this complex process, calories in food and beverages are combined with oxygen to release the energy your body needs to function.

Question 3

What are the different types of nutritions?

Answer 3

Autotrophic nutrition and heterotrophic nutrition.

Question 4

What are organic substances and give some examples.

Answer 4

Organic substances are those substances that are originally made by plants the examples of organic substances are carbohydrates vitamins lipids and proteins.

Question 5

What are inorganic substances and some examples.

Answer 5

Inorganic substances are those which plants use to make organic substances for example carbon dioxide water and minerals from air and the soil.

Question 6

What is carbohydrates made from?

Answer 6

Carbon dioxide and water.

Question 7

What is photosynthesis?

Answer 7

Photosynthesis is the process of manufacturing carbohydrates using carbon dioxide and water and energy from the light.

Question 8

What is chlorophyll?

Answer 8

Chlorophyll is the pigment that makes the plants look green it is kept inside the chloroplasts of plant cells when sunlight falls on a chlorophyll molecule some of the energy in the light is absorbed the chlorophyll molecules and releases the energy the release energy combines carbon dioxide with water with the help of enzymes inside the chloroplast the glucose that is made in the process contains energy that was originally in the sunlight so in the process light energy is transferred to chemical energy.

Question 9

What is the balanced equation for photosynthesis?

Answer 9

6CO2 + 6H2O —–> C6H12O6 + 6O2

Question 10

What is the broad flat part of the leaf called?

Answer 10

Lamina which is joined to the rest of the plant by a leaf stalk.

Question 11

What run through the leaf stalk?

Answer 11

Vascular bundles which then form the veins of the leaf.

Question 12

What is the epidermis?

Answer 12

The top and bottom of the leaf are covered with a layer of closely fitting cells called the epidermis.

Question 13

Why do they not contain chloroplasts?

epidermal cells

Answer 13

To allow sunlight to penetrate through it and reach all the cells quickly.

Question 14

What is the cuticle and which cells create the cuticle?

Answer 14

The cells of the upper epidermis often secrete a waxy substance that lies on top of them it is called the cuticle and it helps to stop water evaporating from the leaf.

Question 15

Where are stomata present?

Answer 15

In the lower epidermis.

Question 16

What are stomata?

Answer 16

They are small openings.

Question 17

What are guard cells?

Answer 17

Each stoma is surrounded by a pair of sausage shaped cells guard cells they open and close the hole and unlike other cells in the epidermis they do contain chloroplasts.

Question 18

What are the middle layers of the leaf called?

Answer 18

Mesophyll layers.

Question 19

What are the two different mesophy layers?

Answer 19

Palisade mesophyll and spongy mesophyll.

Question 20

How are palisade mesophyll cells arranged?

Answer 20

There are arranged like a fence or palisade and they form the palisade mesophyll.

Question 21

How are spongy mesophyll cells arranged?

Answer 21

There are arranged quite loosely with large air spaces between them they form the spongy mesophyll.

Question 22

What does each vein contain?

Answer 22

Each vein contains large thick walled xylem vessels for carrying water there are also smaller thin walled phloem tubes for carrying away sucrose and other substances that the leaf has made.

Question 23

What percentage of the air is carbon dioxide?

Answer 23

0.04%.

Question 24

What are the raw materials needed for photosynthesis?

Answer 24

Carbon dioxide water and sunlight.

Question 25

How does carbon dioxide get into a leaf?

Answer 25

The leaf is held out into the air by the stem and the leaves stalk and it’s large surface area helps to expose it to as much as air as possible the carbon dioxide can get into the leaf through the stomata it does this by diffusion. Behind each stoma is an airspace which connects up with other air spaces between the spongy mesophyll cells the carbon dioxide can therefore diffuse to all the cells in the leaf it can then diffuse through the cell wall and the cell membrane of each cell and into the chloroplasts.

Question 26

How is water obtained by the leaf?

Answer 26

It is obtained from the soil it is absorbed by the root hairs and carried up to the leaf in the xylem vessels.

Question 27

How does the thinness of the leaf help in photosynthesis?

Answer 27

The thinness of the leaf allows the sunlight to penetrate right through it and reach all the cells to help this the epidermal cells are transparent with no chloroplasts.

Question 28

Why are palisade cells arranged end on?

Answer 28

To keep as few cell walls as possible between sunlight and the chloroplasts.

Question 29

Why are the chloroplasts inside palisade cells often arranged broadside on?

Answer 29

to expose as much chlorophyll as possible to sunlight.

Question 30

Why are xylum vessels within short distance of every mesophyll cell?

Answer 30

Water is used in the process of photosynthesis so the cells are using it up quickly and the present of xylem vessels will help to supply water to the cells in the leaf.

Question 31

Why are phloem tubes within short distance of every mesophyll cell?

Answer 31

To take away sucrose and other organic products of photosynthesis.

Question 32

What are the uses of glucose?

Answer 32

It is used for energy, it is stored as starch, it is used to make proteins and other organic substances and it is changed to sucrose for transportation.

Question 33

How is glucose used for energy?

Answer 33

Glucose will be broken down by respiration to release energy by the leaf.

Question 34

Three reasons why glucose is not a good storage molecule?

Answer 34

First it is soluble in water and a quite reactive substance being reactive it might get involved in chemical reactions where it is not wanted secondly it would dissolve in the water in and around the plant cells and might be lost from the cell thirdly when dissolved it would increase the concentration of the solution in the cell which could affect osmosis.

Question 35

What is glucose converted to for storage?

Answer 35

It is converted into starch to be stored as starch. It is a polysaccharide made of many glucose molecules joined together being such a large molecule it is not reactive and not very soluble it can make it can be made into granules which can be easily stored inside the chloroplasts.

Question 36

How can plants make amino acids?

Answer 36

Plants can also use the sugars they have made in photosynthesis to make amino acids which can be built up into proteins to do this they need nitrogen.

Question 37

What do plants use instead of nitrogen?

Answer 37

Even though the air around us is 78% nitrogen this is completely used to plants because it is very unreactive plants have to be supplied with nitrogen in a more reactive form usually as nitrate ions.

Question 38

How do plants obtain nitrate ions?

Answer 38

They absorb nitrate ions from the soil through their root hairs by diffusion and active transport the nitrate ions.

Question 39

What is active transport?

Answer 39

Active transport is the movement of cells from a lower concentration gradient to the higher concentration gradient using ATP.

Question 40

How are protein molecules made?

Answer 40

The nitrate ions combined with glucose to make amino acids the amino acids are then strong together to form protein molecules.

Question 41

What does the plant need to make chlorophyll?

Answer 41

They need nitrogen to do this and also another element- magnesium the magnesium like the nitrate ions is obtained from the soil.

Question 42

Explain why a plant that does not get enough nitrate ions has weak growth?

Answer 42

Because it needs nitrogen to make proteins and proteins make new cells and if the plant is not able to make new cells it will not have good growth.

Question 43

What is nitrogen deficiency?

Answer 43

Weak growth and yellow leaves.

Question 44

What’s the deficiency of magnesium?

Answer 44

Yellowing between the veins of the leaves.

Question 45

Why can’t glucose be used for transportation?

Answer 45

A molecule has to be small and soluble to be transported easily glucose has both of these properties but it is also rather reactive it is therefore converted to the complex sucrose to close to be transported to other parts of the plant sucrose molecules are also quite small and soluble but less reactive than glucose the dissolve in the sap in the phloem vessels and can be distributed to whichever parts of the plant need them.

Question 46

Why will a leaf which contains starch not turn black immediately if iodine solution is added onto it?

Answer 46

This is because the starch is inside the chloroplasts in the cells iodine solution cannot get through the cell membranes to reach the starch and react with it.

Question 47

What’s another difficulty you face when you add iodine solution onto the leaf?

Answer 47

Another difficulty is that the green color of the leaf and the brown iodine solution can look black together.

Question 48

Why do you put a leaf into boiling water before testing it for starch?

Answer 48

To break the cell membranes down.

Question 49

Why was the leaf put into alcohol after being put into boiling water?

Answer 49

So that the chlorophyll is removed by dissolving it out with alcohol.

Question 50

What is the control in an experiment?

Answer 50

The control is given everything it needs including the substance being tested for.

Question 51

What is the experimental plant?

Answer 51

The important thing is that the control has all the substances it needs while the experimental plant or leaf is lacking one substance.

Question 52

Why is it important for leaves to not have any starch before an investigation?

Answer 52

It is very important that the leaves you are testing should not have any starch in them at the beginning of the investigation if they did and you found that the leaves contained starch at the end of the investigation you could not be sure that they had been photosynthesizing the starch might have been made before the investigation began.

Question 53

How do you destarch plants?

Answer 53

The easiest way to do this is to leave them in a dark cupboard for at least 24 hours the plant cannot photosynthesize while they are in the cupboard because there is no light so they use up their stores of starch to be certain that they are thoroughly destarched just leave for starch before you begin.