As 90928

Demonstrate understanding of biological ideas relating to the life

cycle of flowering plants

Plant growth and photosynthesis

L.ODescribe primary growth and the significance of meristematic tissue

Do Now – The following statements are incorrect. Rewrite them, making them correct and adding a reason for the change you make.1. Asexual reproduction is more complex than sexual.

eg. Asexual reproduction is less complex than sexual, because it does not involve flowers and gametes2. Asexual reproduction involves the production of gametes3. Sexual reproduction results in genetically identical offspring4. The offspring of asexual reproduction are dispersed away from the parent plant5. Should conditions change, the offspring of sexual reproduction may all die.

Primary growth

Primary growth

Primary growth

Primary growth in plants is all about growing in length. This growing occurs in two areas – the tip of the root (ROOT TIP) and the tip of the shoot (SHOOT TIP). Both these areas contain meristem tissue – this means they have unspecialised cells that will divide to make more cells and make the area grow longer. Once the new cells are produced they elongate and become bigger, and then differentiate into the specialised cells eg. Root hair cells in the roots.

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L.ODefine tropismDescribe the advantages of tropisms

Do NowWhat cells are responsible for primary growth in a plant?

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There are many types of tropisms :• Phototropism• Geotropism• Thigmotropism• Hydrotropism• Chemotropism• Thermotropism

3 main types

TROPISMPlant growth in response to a

stimulus (“tropo” – ”turn”)

*Can be positive or negative

GEOTROPISM Geotropism is the growth of a plant in response to gravity.

Positive Geotropism

It is the growth of a plant towards the center of the earth-down with

gravity.Ex. roots growing down

Negative Geotropism It is the growth of a plant away

from the center of the earth-opposite from the pull of gravity

Ex. stems grow upNEXT

Positive Geotropism

Negative Geotropism

(“Geo” – Earth)

IMPORTANCE OF GEOTROPISM

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• Pulls roots down to anchor a plant

• Roots can get needed water and minerals if they stay in the soil

http://www.youtube.com/watch?v=iFCdAgeMGOA&feature=related

CORN TROPISM LAB

PHOTOTROPISMThe growth response of a plant in response to light direction is

called phototropism.

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(“Photo” – light)

Ex. Stems growing toward the window to get to the light

Tropism

http://plantsinmotion.bio.indiana.edu/plantmotion/movements/tropism/tropisms.html

IMPORTANCE OF PHOTOTROPISM

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Enables leaves to be in the best position possible to receive adequate light for

photosynthesis

http://www.darienps.org/teachers/otterspoor/botany/tropisms/Gravitropismwlight.jpg

THIGMOTROPISMThigmotropism is the growth

of a plant in response to touch/contact.

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(“Thigmo” – “touch”)

Tendrils on a sweet pea

Photo by Christopher Meloche

Vines growing on a wall or fence

HYDROTROPISM

Hydrotropism is the growth in response to water. Ex. roots

growing toward moisture

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(“hydro” – “water”)

THERMOTROPISMThermotropism is the tendency of plants or other

organisms to bend toward or away from heat.

Ex. curling of Rhododendron leaves in response to cold temperatures.

ChemotropismChemotropism is movement caused by chemical stimuli.

Ex. Growth of a pollen tube is always towards the ovules so that reproduction can occur

(“Therm” – “heat”)

(“Chemo” – chemical”)

L.ODescribe how the structure of roots is related to their function

Key wordsRoot hairs TranspirationTurgidFlaccidosmosis

Do Now- Write down the name of the process that each of these statements are describing

1. When the pollen and egg fuse together to form a new individual

2. Reproduction in which offspring are formed from just one parent

3. The transfer of pollen from the anther to the stigma4. The movement of seeds away from the parent plant

Osmosis

The movement of water from a high to a low concentration

across a semi-permeable membrane

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The photo on the left is a picture of the microscopic root hairs on a root. Explain how these hairs help the roots carry out their job.

Food Storage Roots

All roots have the same basic functions. These are Absorb ____________ and ______________.

To ______________ the plant firmly in the ground.

Some roots also act as a _________ space for food made by the plant.

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L.ODescribe the function of a plant stem

Key wordsMeristemTerminal budXylemPhloemCambiumVascular bundle

Do Now

Highlight any words we have covered since we last looked at the key word sheet

Water and minerals move up while sugar moves down

Xylem:Xylem carry water from the roots to the upper parts of the plant. The movement is powered by transpiration. Water evaporates from the top, and water below moves to replace it.

Phloem:Phloem carry sugar and water from upper parts of the plant to lower parts to supply nutrients to the rest of the plant.

Transportation within Stems

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L.ODescribe the process of secondary thickening

Monocotyledon vs dicotyledon

• Dicot stems have a pith in the center with vascular tissues in a distinct ring visible in a cross section.

Types of Stems: Dicot

• In vascular plants, secondary growth or, perhaps more accurately, secondary thickening is the result of the activity of the vascular cambium. The latter is a meristem that divides off cells: the cells on the inside of the meristem (the adaxial side) will become secondary xylem, while the cells on the inside (the abaxial side) will become the secondary phloem. This growth increases the girth of the plant, rather than its length, hence the phrase "secondary thickening". As long as the vascular cambium continues to produce new cells, the plant will continue to grow more stout. If this is kept up over many years, this process produces wood.

• Because this growth ruptures the epidermis of the stem, woody plants also may have a cork cambium that develops among the phloem. The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss. If this is kept up over many years, this process may produce a layer of cork. In the case of the cork oak it will yield harvestable cork.

Secondary Growth

L.OCompare and contrast primary and secondary growth in plants

Do Now1. Do you think this flower

is pollinated by wind or insects

2. What features show it is wind/animal pollinated

3. Why do these help it get pollinated?

L.OIdentify which foods contain starch

Do Now1. Where in a plant does secondary thickening occur?

What is starch?

Starch or amylum is a carbohydrate consisting of a large number of glucose units joined by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store.

Starch:

Plants store glucose as the polysaccharide starch. The cereal grains (wheat, rice, corn, oats, barley) as well as tubers such as potatoes are rich in starch.

L.OCarry out a

Do Now1. What do we use Iodine to test for?

L.ODescribe how to carry out a starch test

Do Now1. What do we use Iodine to test for?

(a)Explain how the thickness of the stem increases over a number of years. In your answer, you should:

identify the tissue in the stem where secondary thickening occurs

explain how the changes to those tissues in the stem allow the stem of the plant to grow thicker.

L.ODiscuss the conditions necessary for photosynthesis

Do NowWrite the word equation for photosynthesis

Aim: To find out if light is needed for making starch

Conclusion:Light is needed for photosynthesis to produce starch in leaves.

Aim: To find out if carbon dioxide is needed for making starch

Aim: To find out if carbon dioxide is needed for making starch

Conclusion: Geranium plants only produce starch by photosynthesis if carbon dioxide is available.

Conclusion:The green substance in leaves (chlorophyll) is needed for photosynthesis to produce starch in leaves.

L.OName the products of photosynthesis and explain why they are important to life on earth

Do NowComplete the reflection time section on pg 64

Photosynthesis

Carbon dioxide Water In the

chloroplast Glucose Oxygen

Sunlight

The chemicals used in photosynthesis are carbon dioxide (CO2) and water (H2O).

The chemicals produced are Glucose (C6H12O6) and oxygen (O2).

This process happens in the chlorophyll which is in chloroplast and energy from the sun is needed

L.OExplain how the rate of photosynthesis is affected

Do NowComplete the reflection time section on pg 64

Rate of photosynthesis

Carbon dioxide Water Starch Oxygen

Sunlight

1. Sunlight2. Carbon dioxide3. Water4. temperature

What affects the rate of

photosynthesis?

L.ODescribe the adaptations a leaf has to enable photosynthesis to occur

Do NowComplete the reflection time section on pg 68

The Plant Body: Leaves

• FUNCTION OF LEAVES – Leaves are the solar energy

and CO2 collectors of plants. – In some plants, leaves have

become adapted for specialized functions.

EXTERNAL ANATOMY

• Leaves possess a blade or lamina, an edge called the margin of the leaf, the veins (vascular bundles), a petiole, and two appendages at the base of the petiole called the stipules.

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EXTERNAL ANATOMY

LEAF – Internal Anatomy

Leaf – Internal Anatomy

Internal and External Views

Why is this important for photosynthesis?

Spongy layer leaving air spaces

Still carry out photosynthesis but the spaces allow gases to move around them (O2 and CO2)

Stomata and guard cells at the bottom

If the stomata were on the top of the leaf, water (that is vital in the process of photosynthesis) would be lost by transpiration

Leaves are flat and thin The flatness of leaves works to expose the chloroplasts to more light and to increase the absorption of carbon dioxide.

Chloroplasts are mostly at the top of the leaf

So they can be exposed to as much sunlight as possible to carry out photosynthesis

Vascular bundles containing xylem and phloem

Xylem transports water to the cells, phloem transports the glucose away

L.OI can explain the process of photosynthesis and is importance

Discuss how a plants might maximise its ability to carry out photosynthesis.

In your discussion you should include the following points and explanations:• The process of photosynthesis, raw materials and products• The factors that may influence the rate of photosynthesis and

how each part contributes to the process• A description of the parts of the plant involved in

photosynthesis and how each part contributes to the process• Any examples where plants may have specific adaptations to

maximise photosynthesis