Evolution Of Plants

Question 1

What are the modern influences on plant evolution?

Answer 1

1. Urbanisation- changing ecosystems requires adaptation
2. Climate- changes in structure due to warming environment
3. Dispersal by humans causing hybrids
4. Breeding- humans have forced the evolution of plants for agriculture

Question 2

What are angiosperms ?

Answer 2

Flowering plants

Question 3

When did angiosperms evolve ?

Answer 3

1.35 million years ago

Question 4

When did land plants evolve ?

Answer 4

475 million years ago

Question 5

What is suggested to be the link between Gnetophytes and Angiosperms ?

Answer 5

Bennettitales

Question 6

Describe the structure of the flower ?

Answer 6

1. Sepal- the outer part of the flower
2. Petals
3. Stamen- produced pollen, typically consisting of an anther and a filament
4. Carpel- composed of an ovary, a style and a stigma

Question 7

What structure did early flowers most likely have ?

Answer 7

Tepals rather than sepals and petals
So the flower was arranged in a 3 layer whorl rather than 4 that they now have

Question 8

What are key trends that occurred in evolution of flower structure ?

Answer 8

1. Flowers became less complex and more aligned with a common format
2. Floral structures simplified and flattened from complex spiral arrangements to simpler symmetrical arrangements
3. Radial symmetry became less common compared to bilateral symmetry
4. Carpel tended to be inferior to the flower rather than superior

Question 9

What are the evolutionary advantages of having pollen ?

Answer 9

1. Fertilisation without water- pollen allows sperm to reach the egg without needing water, making it possible for plants to live in dry environments.
2. Dispersal over distance- pollen can be carried by wind, insects etc, increasing the range and likelihood of fertilisation between plants
3. Protects the sperm from desiccation (drying out)

Question 10

What are the evolutionary advantages of having seeds ?

Answer 10

Early plants used spores and water borne gametes which are not useful on land.
1. Protection of the embryo
2. Nutrient storage

Question 11

Describe the co-evolution of flowering plants and pollinators

Answer 11

The plant spreads lots of pollen, but with little energy wasted on encouraging pollinators.
The pollinator gets lots of food for minimal effort.
Many flowers have been uniquely structured for the parts of the pollinator.

Question 12

Describe seed dispersal co-evolution?

Answer 12

Plants have evolved fruits that are attractive to animals to eat and then later excrete the seeds elsewhere