Plant Evolution

Question 1

Advantages to plant life on land

Answer 1

Light no longer a limiting factor, more O2 and CO2

Question 2

Disadvantages to plant life on land (5)

Answer 2

Gravity (no lignin), less water, water & nutrients in different locations than gases, reproduction, environmental stress (UV, temperature, H2O changes)

Question 3

How did plants adapt to maintain moisture? (3)

Answer 3

1. Water transport systems: soil –> leaves. 2. Cuticle and stomata to avoid & regulate H2O loss. 3. Pollen and seeds resistant to dehydration

Question 4

How did plants adapt to reproduce? (3)

Answer 4

Animal pollination, fruit, targeted pollen and seed dispersal

Question 5

How did plants adapt vs gravity? (2)

Answer 5

Supporting plant body with thicker cell walls and addition of lignin

Question 6

How did plants adapt to gain protection vs (a)biotic stress?

Answer 6

2ndary metabolites: chemical defense against pests and climate.

Question 7

Adapting to life on land meant dealing with water, nutrients and gases in different places. How did plants deal with this? (3)

Answer 7

1. Larger leaves = more photosynthesis. 2. Large plants = shoot and root system. 3. Transport systems to move nutrients = xylem and phloem

Question 8

Why are some plants small and others tall?

Answer 8

Vascular plants vs non-vascular plants, since non-vascular plants (mosses, ferns) lack vascular tissues and lignin.

Question 9

What is primary growth?

Answer 9

Used to make plants grow tall; the addition of elongated and differentiated cells lengthens the stem or root via the apical/primary meristem.

Question 10

What is secondary growth and how does it occur?

Answer 10

Secondary growth is used for plants to grow thick and only takes place in eudicots via lateral meristems: the vascular and cork cambium.

Question 11

What is the vascular cambium and how does secondary growth occur within it?

Answer 11

The vascular cambium is located between the xylem and phloem. The xylem grows horizontally on both sides of the vascular cambium (inwards and outwards).

Question 12

What is the cork cambium and how does secondary growth occur within it?

Answer 12

The cork cambium is located on the outside of the phloem and extends outward to form 2ndary dermal tissue and bark (with 2ndary phloem).

Question 13

What is bark made of?

Answer 13

Periderm, 2ndary phloem, phelloderm, cork cells, cork cambium.

Question 14

What is wood made of?

Answer 14

The 2ndary xylem (lignified cell walls)