Plants

Question 1

Name the plant organs and plant tissues.

Answer 1

Plant organs include:

• stems
• roots
• leaves
• flowers

Plant tissues include:

• epidermal tissues that cover the plant
• mesophyll, where photosynthesis takes place
• xylem and pholem that transport substances around the plant.

Question 2

Understanding the levels of organisation

Answer 2

Palisade cell –> Palisade tissue –> Leaf (organ) –> Plant (organism)

Muscle cell –> Muscle tissue –> Heart (organ) –> Animal/Circulatory system

Question 3

Name the organelles where energy is released in respiration.

Answer 3

Mitochondria

Question 4

List three structures found in plant cells that are not found in animal cells.

Answer 4

A cell wall, chloroplasts and a permanent vacuole.

Question 5

What are a group of cells that have a similar structure and function called?

Answer 5

A tissue

Question 6

Is heart a tissue, organ or organ system?

Answer 6

A organ

Question 7

Which animial tissue covers the outside and inside of organs?

Answer 7

Epithelial tissue

Question 8

State two differences between diffusion and active transport.

Answer 8

Diffusion involves the net movement of particles from high to low concentration.

Active transport involves the net movement of particles from low to high concentration. This requires energy from the cell and is therefore an active process.

Question 9

State three factors that increase rate of diffusion.

Answer 9

Any three from: Steep concentration gradient; large surface area across which to diffuse; increasing the temperature; A short distance for the particles to diffuse across.

Question 10

What is meant by the term osmosis?

Answer 10

Osmosis is the diffusion of water from a dilute solution to a more concentrated solution, through a semi- or partially permeable membrane.

Question 11

Explain how osmosis is involved in plant support.

Answer 11

Water enters the plant cells by osmosis and pushes against the inelastic cell wall. The pressure inside the cells increases and holds the plant upright.

Question 12

Sugguest why a plant begins to wilt if it is flooded by salty water.

Answer 12

The seawater around the roots is a higher concentration than the content of the root cells, so water leaves the plant by osmosis. The cells then become flaccid and the plant wilts.

Question 13

Explain what will happen to the lenght of a carrot that is soaked in distilled water for an hour.

Answer 13

The carrot will increase in length because its cells take in water by osmosis.

Question 14

Write the chemical equation for photosynthesis.

Answer 14

6CO₂ + 6H₂0 -> C₆H₁₂O₆ + 6O₂

Question 15

Describe and explain how the rate of photosynthesis is affected by temperature.

Answer 15

When temperature rises, the rate of photosynthesis increases. This is because the enzymes and substrates used in photosynthesis are colliding more frequently. Temperature increases above the optimum will denature the enzymes and so the rate of photosynthesis will then fall to zero.

Question 16

Describe how gases enter and leave a leaf.

Answer 16

Gases diffuse through stomata, into and out of the air spaces of the leafs.

Question 17

How is the internal surface area to volume ration of a leaf made very large?

Answer 17

The cells of the spongy mesophyll are very loosely packed, with many air spaces between them. This exposes a very large surface area of cells to the air and so produces a high surface are to volume ratio.

Question 18

Explain how the broad, thin shape of a leaf adapts the leaf for the photosynthesis.

Answer 18

The broad shape gives the leaf a large surface area exposed to sunlight. The thin shape means there is only a short distance for gases to diffuse in and out of the stomata.

Question 19

Name the two mineral ions needed by the plants.

Answer 19

Magnesium, Nitrates

Question 20

Which of theses mineral ions is needed by the plant to make a) protein? b) chlorophyll?

Answer 20

a) Nitrates b) Magnesium

Question 21

a) what is a variegated leaf? b) How can a variegated leaf tell you about photosynthesis?

Answer 21

a) A leaf that has some parts that are white because they don’t contain chlorophyll and other parts that have chlorophyll in them
b) Variegated leaves only contain starch in the parts that contain chlorophyll. This shows that chlorophyll is needed for photosynthesis.

Question 22

Describe how you would show that oxygen is given off during photosynthesis.

Answer 22

Trap pondweed under an inverted glass funnel in a beaker of water and illuminate the weed. Collect the bubbles of gas given off in an inverted test tube of water, then test the gas with a glowing splint. The splint relights, which shows it’s oxygen.

Question 23

When does a plant:

a) respire? b) photosynthesise?

Answer 23

a) All the time
b) When the plant is in the light

Question 24

What are stomata and why are they important?

Answer 24

Microscopic pores on the underside of leaves that allow gases to pass in and out

Question 25

Why are air spaces in leaves important?

Answer 25

Air spaces allow gases to circulate inside the leaf.

Question 26

Explain why plants release oxygen during the day and carbon dioxide at night.

Answer 26

Plants photosynthesise fast during the day and therefor produce more oxygen than they use for respiration. Plants continue to respire at night but do not photosynthesise, so they produce carbon dioxide but do not produce oxygen.

Question 27

What is transpiration?

Answer 27

Transpiration is the loss of water vapour from a leaf, by evaporation from cell surfaces and diffusion through the stomata.

Question 28

Name two substances transported in the: a) xylem

b) phloem.

Answer 28

a) Water and mineral salts
b) Amino acids and sucrose

Question 29

Name three environmental factors that speed up the rate of transpiration.

Answer 29

Any three from: higher temperature; wind; low humidity; increased light intensity

Question 30

Explain how water enters root hair cells from the soil.

Answer 30

Water enters root hair cells from the soil by osmosis across the partially permeable cell membrane.

Question 31

Describe how you could measure the rate of transpiration.

Answer 31

Use a mass potometer. Submerge the roots of a leafy plant in water in a sealed bag. Put the bag in a beaker and stand it on a digital balance. Record the fall in mass due to transpiration.

Question 32

What is potometer used for?

Answer 32

To measure the rate of transpiration

Question 33

Explain why high light intensity increases the rate of transpiration.

Answer 33

It causes the stomata to open.

Question 34

Explain how and why an increase in temperature affects the rate of transpiration.

Answer 34

Higher temperatures increase transpiration rate because they increase the rate of evaporation of water from cells inside the leaf. This increases the concentration gradient for water vapour between the leaf air spaces and the atmosphere, so water vapour diffuses more quickly out through the stomata.

Question 35

Explain how high humidity affects the rate of transpiration.

Answer 35

High humidity decreases transpiration because the high concentration of water vapour outside the stomata reduces the concentration gradient between the leaf air spaces and the surrounding air. So diffusion of water vapour out of the leaf is slower.

Question 36

Under what environmental conditions would you expect a plant to be most likely to wilt?

Answer 36

Hot, sunny and dry conditions

Question 37

Name the parts of flower that produce:

a) male gametes
b) the female gamete.

Answer 37

a) Anther; (accept stamen)
b) Ovary

Question 38

What do we mean by the term pollination?

Answer 38

Transfer of pollen from anther to stigma

Question 39

List three features of:

a) wind-pollinated flowers
b) insect-pollinated flowers

Answer 39

a) Any three from: Large feathery stigmas; Light smooth tiny pollen grains; Long filaments with anthers that hang outside the flower; Small dull flowers

b) Any three from: Scented, colourful and large flowers; Nectaries; Spiky or sticky pollen grains; Sticky stigmas

Question 40

Describe how the male gamete reaches the ovule from the stigma of a plant.

Answer 40

The pollen grain grows a pollen tube down the style through the micropyle and into the ovule. The male gamete passes down the pollen tube into the ovule and fuses with the female gamete.

Question 41

Name: a) embryo shoot b) the embryo root c) the embryo leaves d) the seed coat.

Answer 41

a) Plumule b) Radical c) Cotyledons d) Testa

Question 42

List three factors needed for germination.

Answer 42

Water, oxygen, warmth

Question 43

Plants produced by asexual reproduction are clones of their parent. What does this mean?

Answer 43

Clones are offspring that are genetically identical to their parent.

Question 44

Why are plant responses slower than animal responses?

Answer 44

Plants have no muscles.

Question 45

Explain how a seedling on a windowsill will grow towards the light.

Answer 45

Light from one side causes auxin to accumulate on the dark side. Auxin stimulates cell division and elongation. So growth is faster on the dark side.

Question 46

If a particular weedkiller is toxic to all plants, how can spraying it on a lawn kill the dandelions but not the grass?

Answer 46

Dandelions have wider leaves/a greater surface area. So they will absorb more toxin.

Question 47

When seeds start to germinate, why is it more important to respond to gravity than to light?

Answer 47

Because many seeds germinate in the dark/there is no light in soil.

Question 48

State two reasons why photosynthesis is vital to life on Earth.

Answer 48

Any two from:

• makes food
• makes oxygen
• only route for energy into ecosystem

Question 49

Write out the overall equation for photosynthesis, in words.

Answer 49

carbon dioxide + water ( in presence of ) light energy, chlorophyll –> glucose + oxygen

Question 50

If a cell’s cytoplasm contains a lot of glucose, it will absorb a lot of water due to osmosis. Why does the cell not have the same problem with starch?

Answer 50

Starch is insoluble.