Leaves and plant form/function

Question 1

Describe bryophyte leaves?

Answer 1

Liverworts don’t have leaves. Mosses are different leaves to the other land plants – they are more tolerant of desiccation than most other leaves on land plants.

Question 2

Describe fern fronds?

Answer 2

Fern fronds are different in the way that the sporangia (which produce the spores) are produced on the fronds.

Question 3

Describe gymnosperm leaves?

Answer 3

Pine needle is a half way structure between a shoot and a leaf.

Question 4

Describe angiosperm leaves?

Answer 4

A leaf is described as a structure that grows from a stem and where the structure meets the stem, there is a bud.

Question 5

Types of leaves?

Answer 5

• Microphylls – single leaf trace (vein)
• Eudicot megaphylls – multiple leaf traces (veins) in a reticulate (networked) pattern
• Monocot megaphylls – multiple leaf traces (veins) in a parallel arrangement pattern

Question 6

Why are the leaves of Monstera deliciosa fenestrated?

Answer 6

Possible reasons included reducing wind resistance, let water through, reducing herbivory, letting light through or this species is bad at making leaves.

Question 7

Why are younger leaves coloured differently?

Answer 7

Could be to reduce herbivory or UV damage, or might just be part of development. Unknown why leaves change colour in autumn.

Question 8

How do plants deal with water stress?

Answer 8

Discarding leaves to limit transpiration losses or making drought resistant leaves. Can happen due to drought or v cold temperatures freezing the soil.

Question 9

How do plants float on the surface of water?

Answer 9

Trap air… 1. In empty cells in leaf petiole (water lilies) 2. In between hairs (water lettuce) 3. In leaf lamina (duck weed) 4. In empty cells in the veins (Victoria water lily)

Question 10

How many times have carnivorous leaves evolved?

Answer 10

At least 5. Example of convergent evolution. Despite all of these plants are unrelated and evolved independently, they all use the same enzyme to digest prey. What’s striking is that the same genes from non-carnivorous ancestors have been recruited for carnivorous purposes. Namely, proteins originally involved in protecting the plants against diseases and other stressors eventually turned into digestive enzymes. This ability likely appeared as a means for the plants to cope with nutrient-poor environments. Trapping and digesting animals can be indispensable in this situation.

Question 11

Uses of scented leaves?

Answer 11

Attract animals such as pollinators Repel herbivores Inter-plant warning/communication.

Question 12

Uses of hairy leaves?

Answer 12

Reduce water loss by evaporation Insulation Stinging hairs for protection

Question 13

What are the different whorls of organs in flowers?

Answer 13

Calyx (sepals) Corolla (petals) Androecium (stamen) Gynoecium (carpel) Flowers can contain any number of these.

Question 14

How can you tell if plants have fused petals?

Answer 14

Notches in the petals or find mutants with more petals (gene for fusing knocked out)

Question 15

Example of the fact that not all tubes are petals?

Answer 15

Daffodil. Stamens are fused to the tube and the trumpet is an extension of the stamens. The tube is a tissue which joins together the stamens. Was more obvious in the relatives.

Question 16

Define an inflorescence?

Answer 16

A bunch of flowers, usual to have multiple.

Question 17

Which plants have a variable number of plant organs?

Answer 17

Magnolias are an example

Question 18

How is pollen released from the anther?

Answer 18

Can split open and display all its pollen or pollen comes out of a small hole.

Question 19

Define monoecious

Answer 19

One house – plants with either perfect flowers or with both male and female flowers on the same plant.

Question 20

Define dioecious

Answer 20

Two houses – plants having staminate and carpellate flowers on separate plants.

Question 21

Issues with pollination

Answer 21

Make sure that the pollen is taken to the same species of plant. Major issue if the pollinating animal dies out, as can’t pollinate certain flowers. Has potential to become incredibly self-inbred.

Question 22

Types of pollinator?

Answer 22

Bird, moth and bee. Groups of flowers are normally pollinated by the same animal.

Question 23

How is the correct stigmatic surface found?

Answer 23

Some species produce millions of pollen grains which are moved by the wind and statistically will pollinate another plant. Others use visual, olfactory and taste stimuli to attract an animal intermediary.

Question 24

Non-biological pollination?

Answer 24

1. Wind. Evolved many times and is the most common pollination syndrome. Not advanced, but not the primitive state. Pollen tends to be small, dry, smooth and non-adhesive. All British timber trees are pollinated by wind. Don’t need to attract wind. Some forcibly eject pollen. Birch catkins have flaps to prevent pollen falling out due to gravity – must be blown out. Lock and key mechanism of pollen recognition to provide water for germination. 2. Water Water pollination can result in premature germination by accidental absorption of water. Must be very waterproof pollen. Aquatic plants are rarely pollinated by water.

Question 25

Biological pollination?

Answer 25

Certain flower types are suited for certain pollinators. 1. Bee Pollinators Often bell shaped or gullet shaped, helps to prevent other animals taking the nectar. Might require a large amount of force to open them up. 2. Moth Pollinators Night flowering plants. (Night flowering cactus). Night scented Brugmasia knightii. British native honeysuckle is heavily scented at night to attract night flying moths 3. Bird Pollinators Often red, tubular and full of nectar (bird wants a big reward). Delicate pollinators, esp compared to beetles. Anigozanthos manglesii flower, after one flower is pollinated, it bends to the side for pollination of the next flower 4. Bat Pollinators Robust flowers with a musty smell, held on edge of tree or on a very long stalk. Bat uses sensors to determine whether the flower is front on, or side on. 5. Possum Pollinators Important in Australia and NZ 6. Fly Pollinators Unspecialised. 7. Mollusc Pollinators Very slow!

Question 26

Do pollination syndromes exist?

Answer 26

Only for around 30 species.

Question 27

What is a pollination syndrome?

Answer 27

Suites of flower traits that have evolved in response to natural selection imposed by different pollen vectors, which can be abiotic (wind and water) or biotic, such as birds, bees, flies, and so forth.

Question 28

Does pollination behaviour drive speciation?

Answer 28

Not always

Question 29

What are pollination syndromes based on?

Answer 29

Attraction and reward

Question 30

Describe attraction in pollination syndromes?

Answer 30

Attraction may be through visual signals (could be UV), or scent. Convergent evolution with the evolution of smell, and the evolution of the animal’s preference. Big correlation between heat and smell. Attraction & Reward is a strategy open to abuse as a result of mimicry and no reward. Biosynthetic pathways get mixed to produce certain scents. (125 molecules produced), and different parts of the flower can have different scents

Question 31

Describe rewards in pollination syndromes?

Answer 31

Female wasps lay eggs in the neuter flowers (& dies). The born male wasps with find females ( & die). The fertilised females will emerge getting pollinated. Wasp now lays eggs that hatch into only females (only neuter flowers). These will then move to more figs to fertilise again. Nectar is a common reward. Can be scented for attraction and reward. Victoria amazonica: When stigma is receptive, scented with nectar, starch bodies and brood chamber. Day two flower shed pollen onto the Beatles which were trapped. Then go on to fertilise more flowers.

Question 32

What is advergent evolution with an example?

Answer 32

One half of relationship doesn’t change, the other evolves towards it. Mimic other plants, sexual mimicry. Pseudo-copulation: mirror orchid can modify a leaf to look like female bees. Young male bees can’t compare to normal females as it occurs before females appear. The orchid also produces pheromones. Orchid puts pollen onto the bee. Needs to change position on the bee in order to pollinate. Stalk on bee bends so that it can pollinate the stigmatic surface.

Question 33

Where do plants allocate their resources?

Answer 33

-Wind pollinated grass put their effort into producing many more stamens -Bee pollinated orchid put most of energy into specialising one leaf to look like and smell like the female bee -Unspecialised umbellifer: Outer flowers attract pollinators.

Question 34

Why is bee conservation important?

Answer 34

-economic as 1 in 6 of our crops are pollinated by bees. Risk with applying pesticides. -bees are pollinated by same bees which require other species as food source -GM. Maize pollen isn’t capable of moving more than a mile. Necessary to know how far it can travel -Plant conservation. Serapias lingua is pollinated by a species of bee that sleeps in the flower overnight -invasive plants as a result of unspecialised pollinators

Question 35

How can seed dormancy be delayed by dormancy?

Answer 35

-hard seed coat -chemical inhibitors -immature embryo

Question 36

How can dormancy be broken?

Answer 36

-time -leaching -cold temps -heat (fire) -smoke -decay -chemical corrosion -physical abrosion