Plants 4 Lecture

Question 1

What are gymnosperms?

Answer 1

Seed Plants

Question 2

Example of Gymnosperms

Answer 2

Trees with seeds(conifers, pine trees)

Question 3

What is a tree?

Answer 3

Plants with a single stem that can branch and reach large heights thanks to specialized cells. Trees have wood and increase in girth

Question 4

First Tree like plants

Answer 4

-20 m tall
- Skinny stems made up of bundles of lignified xylem

Question 5

Carboniferous Forests

Answer 5

-Fern forests that dominated Pangea. Ferns were tall and skinny because they did not have enough structural support to hold themselves up if they were too tall.

Question 6

Coal Beds(used as fossil fuels today)

Answer 6

The results of carboniferous forests. Ferns were made up of lignin and could not decay because no organisms could break them down.

Question 7

Gymnosperms key innovation: Wood
(How was it created)

Answer 7

1. Trees have a layer of dividing cells under their bark (vascular cambium)
2. The vascular cambium lays down new layers of xylem and phloem which allows the plant to grow outward.
3. The xylem then dies creating creating structural support, ability to move large amounts of water and ability to grow in girth.

Question 8

Why are there tree rings?

Answer 8

The vascular cambium will lay down xylem then the xylem will die. Next year the vascular cambium will expand again and lay more xylem down. Creating a ring pattern in trees.

Question 9

Xylem vs Phloem

Answer 9

Xylem: vascular tissue that conducts water
Phloem: Vascular tissue that conducts sugars

Question 10

What happens if young xylem(near the bark) is killed?

Answer 10

If young xylem is killed, the tree will not expand outwards .

Question 11

What happens if phloem is killed?

Answer 11

Less sugars will be transported throughout the tree

Question 12

Gymnosperm key innovation: Pollen

Answer 12

Male Gametes(pollen): encased in a hardy coat and dispersed by wind
Female Gametes: housed on the adult plant(sporophyte). Male gametophyte burrows its way down to fertilize the egg

Question 13

Homospory vs Heterospory (what plants?)

Answer 13

Homospory: Male/Female spores are the same size (Bryophytes, Ferns)
Heterospory: Spores are two different sizes (seed plants)

Question 14

Advantages of the innovation of Pollen

Answer 14

1. Spores that are housed on females are not exposed to air and less likely desiccate
2. Pollen is dispersed by wind/animals and do not require water for fertilization (no motile sperm)
   3.Plants are now able to live in drier environments because fertilization does not require water and their gametes are more resistant to desiccation.

Question 15

Why is the embryo retained inside the cone until it develops the structure of a seed?

Answer 15

Cone provides protection around the embryo, the embryo is provisioned by the mother, parent plant can decide when to release the seed(fires, droughts, maturity)

Question 16

Spores vs Seeds

Answer 16

Spores:
- Occur in fungi and seedless plants
- Unicellular, Haploid
- Does not store food

Seeds:
- Occur in gymnosperms and angiosperms
-Multicellular, Diploid
-Store food
-Greater environmental tolerance

Question 17

Conifers in a variety of temperatures

Answer 17

Boreal Forest
Specialize in both hot and cold environments:
Cold: thick bark, cones shelters seeds
Hot: thin waxy needles(thermoregulate)
Snow: Cone shaped trees(shed snow)
Windy: Dense wood(less likely to fall)

Question 18

What is the albedo?

Answer 18

Albedo measures the light reflectivity of a surface. Albedo controls the temperature of a surface, if less light is reflected the surface will be hotter.

Question 19

Albedo and trees

Answer 19

Trees are expanding towards the tundra causing less light to be reflected and leading to an increase in temperatures in the tundra which is causing even more conifers to move north.

Question 20

Urban Heat Island Effect

Answer 20

Urbanized Areas Experience higher temperatures than areas around them.
This is because dark materials such as asphalt, sidewalks and dark roofs that absorb heat. Tall buildings also prevent the movement of air and heat dissipation.

Question 21

How can trees help the Urban Heat Island Effect?

Answer 21

1. Trees reflect more light than dark surfaces
   2.Trees cover dark surfaces preventing absorption of heat by them.

Question 22

Cycads

Answer 22

• have motile sperm
  -one of the first species that branched off from ferns
  -slow growing and long lived

Question 23

Ginkgos

Answer 23

-Closest living relative to cycad
-Native to china

Question 24

Conifers

Answer 24

-most diverse group of gymnosperms
-Boreal forest

Question 25

Why are gymnosperms better than vascular plants?

Answer 25

-With wood plants can get even taller
-Better dispersal of sexual offspring(seeds)
-Can live in drier environments (no need for water for fertilization)
-gametophyte is completly protected