Plants and water

​Previous lesson

Testing a leaf for starch​

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​Photosynthesis

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​Destarch a plant

Multiple Choice

What are the products of photosynthesis?

• Glucose & Oxygen

• Water & Oxygen

• Carbon dioxide & Water

• Glucose & Carbon dioxide

Multiple Choice

a. add iodine to the leaf b. boil leaf in water c. boil leaf in alcohol d. rinse leaf in water The correct sequence used to test a leaf for starch from the steps above is:

• a b c d

• b c d a

• c d a b

• d c a b

Multiple Choice

When testing a leaf for starch why is it necessary to boil it in ethanol first?

• To break open the plant cells

• To release the starch form the cells

• To kill the plant cells

• To remove the green chlorophyll from the leaf

Multiple Choice

The diagram shows the apparatus used in an investigation to measure the rate of oxygen production during photosynthesis. The investigation was repeated several times and the average amount of gas collected was calculated.

Which two factors must be kept constant during this investigation?

• the amount of water in the beaker and the height of the measuring cylinder

• the size of aquatic plant and the amount of gas in the measuring cylinder

• the size of aquatic plant and the duration of exposure to light

• the size of the beaker and the funnel

Multiple Choice

In the presence of starch Iodine changes colour...

• from red/orange to blue/black

• from blue/black to red/orange

• from pink to yellow

• from yellow to green

• from green to white

Multiple Choice

How do we destarch a plant?

• Place a plant in a dark space for at least 24 hours

• Place a plant in the sunlight for a few hours

• Leave a houseplant outside overnight

• Do not water the plant for a week

Multiple Choice

the root of plant take up nitrogen in the form of nitrate from the soil.

What are the nitrates used to make?

• fat

• glucose

• protein

• starch

​Plants and water

​Grade 8 by Lkhagvajargal

​Everyone knows that plants need water.

If you grow plants in pots, you need to water them regularly.

​Water for support

​Plants need water – it helps them to stand upright. Plant cells contain a lot of water, especially inside their vacuoles. A plant cell that has plenty of water is strong and firm. When all the cells in a plant are like this, they press out against each other and make the whole plant firm and well-supported. When a plant cell doesn’t contain enough water, it becomes soft and floppy. When all the cells in a plant are like this, the plant collapses. We say that it has wilted.

​Water for transport

​Plants contain long tubes, called xylem, which transport water from the roots up to the leaves.

There are mineral salts dissolved in the water, and this is how they are transported around the plant.

​Water for cooling

​When the water in the xylem gets into the leaves, it spreads out through each leaf. Some of it evaporates into the air spaces inside the leaf.

When water evaporates, it absorbs heat energy. This cools down the surroundings.

The water evaporating inside a plant leaf helps to keep the plant cool. This is really important for plants that live in very hot environments.

​Water for photosynthesis

​Water is one of the reactants in photosynthesis. Water combines with carbon dioxide, inside chloroplasts, to make glucose and oxygen.

In fact, only a very small proportion of the water taken up by a plant’s roots is used in photosynthesis.

Homework​

COURSEBOOK - ​ Activity 1.3 & Question 1-3 on page 11

​WORKBOOK - Exercise 1.3 How temperature affects water loss

Multiple Choice

What happens to the rate of transpiration as humidity increases?

• Decreases

• Increases

• Reaches equilibrium

• Nothing

Multiple Choice

How will water leave through a leaf?

• As water

• As ice

• As water vapor

• It won't leave

Multiple Choice

What features do root hair cells have that animal cells do not have?

• Nucleus and cytoplasm

• Cell wall and vacuole

• Chloroplasts and cell membrane

• Chloroplasts and no vacuole

Multiple Choice

How does most of the water needed by the plant get into its leaves?

• It enters through the stomata

• The roots absorb it and then it travels up the xylem

• It's made during a chemical reaction in the stem

• The flowers capture water and deliver it to the leaves

Multiple Choice

Roots absorb water into the __.

• Xylem

• Phloem

Multiple Choice

Both the xylem and phloem are considered-

• Stomata

• Leaves

• Roots

• Vascular tissue

Multiple Choice

Opening that allows gas exchange

• Stomata

• Leaves

• Roots

• Vascular tissue

Multiple Choice

Water exits the leaf through the __.

• Stomata

• Flower

• Roots

• Phloem

Multiple Choice

In what plant cell part/structure is water stored?

• chloroplast

• cell wall

• vacuole 

• cytoplasm

Multiple Choice

What is transpiration?

• The evaporation and diffusion of water from inside leaves

• The uptake of water through root hair cells

• The loss of water from leaves by osmosis

• The uptake of water through stem cells

Multiple Choice

What happens to the transpiration rate as light intensity increases?

• It changes

• It stays the same

• It decreases

• It increases

Multiple Choice

How well did you understand the "plant and water"?

• I GOT IT

• I ALMOST GOT IT

• I NEED HELP