Plant Evolution 2

Question 1

Why are seed plants so successful

Answer 1

• They have reduced male and female gametophytes that develop within parental sporophytes
• Pollen and ovules
• Protected seeds
• Evolutionary advantages

Question 2

How does pollen contribute to the success of seeds?

Answer 2

It protects the MALE gametophytes and can be transported by wind or animals

Question 3

What are the evolutionary advantages of seed plant spores?

Answer 3

• Resistance; They may remain dormant for years until conditions are favourable for germination
• Rapid establishment; Seeds have a food supply stored with them
• Rapid dispersal; They do not rely solely on water for transport

Question 4

Approximately when did seed plants evolve?

Answer 4

360 MYA

Question 5

What type of seeds do Gymnosperms bear?

Answer 5

Naked seeds, typically
on cones

Question 6

4 Main groups of gymnosperms

Answer 6

1. Conifers (Coniferophyta)
2. Cycads (Cycadophyta)
3. Ginkgo (Ginkgophyta)
4. Gnetophyta (Gnetophytes)

Question 7

What are the 2 groups of SEED (vascular) plants

Answer 7

1. Gymnosperms
2. Angiosperms

Question 8

What is the order of evolutionary innovations after plants emerged from green algae?

Answer 8

1. Terrestrialization
2. Stomata
3. Vascular tissues
4. Seeds
5. Flowers

Question 9

Which group of plants have gamteophytes protected in cones?

Answer 9

Gymnosperms

Question 10

Which group of plants have gamteophytes protected in flowers?

Answer 10

Angiosperms

Question 11

Describe the production of sperm in seed plants

Answer 11

• Microspores develop into pollen grains, which contain the male gametophytes of plants
• Pollen grains are protected by
  sporopollenin (exine)

Question 12

What is pollination?

Answer 12

The transfer of pollen to the part of a seed plant containing the ovules

Question 13

What advantage does pollen and the production of sperm in seed plants have?

Answer 13

It eliminates the need for water in sperm transport and fertilisation

Question 14

What is the role of ovules in seed plants?

Answer 14

To protect female gametophytes which produce eggs

Question 15

Describe ovules and the production of eggs in seed plants

Answer 15

• An ovule consists of a megasporangium, megaspore, and one or more protective integuments

Question 16

What are integuments?

Answer 16

Protective layers of cells that encase the ovule in plants.

Question 17

How many integuments do angiosperm megaspores have?

Answer 17

One

Question 18

How many integuments do gymnosperm megaspores have?

Answer 18

Two

Question 19

When does the seed develop in seed plants?

Answer 19

When an ovule is fertilised by pollen

Question 20

What is the structure of a seed? (3)

Answer 20

Consists of embryo, stored food (endosperm) and protective coat

Question 21

In what ways does a seeds structure relate to function?

Answer 21

It provides;
- Protection from desiccation
- Nutrient storage for developing embryo
- Dormancy capability until favourable conditions
- Enhanced dispersal mechanisms

Question 22

What are the Reproductive advantages of seed plants?

Answer 22

• Heterospory: Complete separation of male and female gametophytes
• Reduced gametophytes
• Double fertilisation

Question 23

What is meant by gymnosperms having “naked seeds?”

Answer 23

Seeds are not encased in an
ovary/fruit and instead form cones or
strobili

Question 24

Which is the most diverse group of the gymnosperms?

Answer 24

Conifers with ~ 600 species

Question 25

Which environments can confiners inhabit?

Answer 25

A wide range of environments, often harsh

Question 26

What is the function of conifer leaves?

Answer 26

Needle shaped to minimise water loss

Question 27

How does ventilation in needle shaped conifer leaves work?

Answer 27

1 – 2 long veins down centre

Question 28

How does ventilation in scale shaped conifer leaves work?

Answer 28

Several parallel veins

Question 29

What is unique about the reproduction of Cycads and Ginko in the gymnosperm group?

Answer 29

- Cycads and ginko produce pollen but sperm still swim to complete fertilisation - Hence cycads and ginko have flagellated sperm

Question 30

During which evolutionary period did cycads thrive?

Answer 30

The Mesozoic period

Question 31

What is a current issue faced by cycad gymnosperms?

Answer 31

75% of species today are rare/threatened

Question 32

What plant group do cycads resemble

Answer 32

Palms, though they are only distantly related

Question 33

How many ginko gymnosperm species exist today?

Answer 33

One

Question 34

What is the single living species of ginko?

Answer 34

Ginkgo biloba (maiden hair tree)

Question 35

What is a current issue faced by ginko gymnosperms?

Answer 35

They are endangered in the wild

Question 36

In which ways do ginko resemble angiosperms?

Answer 36

The flat leaves and fleshy seeds make it look like an angiosperm – but doesn’t form true fruit or flowers

Question 37

What environment are Gnetophytes adapted to?

Answer 37

Arid

Question 38

What (if any) characteristics do gnetophytes share with angiosperms?

Answer 38

They share **superficial** characteristics with early angiosperms

Question 39

How is sperm delivered to egg in gymnosperms?

Answer 39

The pollen grain grows tube to deliver sperm to egg

Question 40

What is the Evolutionary Significance of gymnosperms?

Answer 40

- Represent a key transition between seedless vascular plants and angiosperms - Demonstrate successful adaptation to terrestrial environments - Many are long-lived with slow growth and reproduction rates - Some species among the largest and oldest organisms on Earth - Several groups ("living fossils") provide insights into ancient plant forms

Question 41

What are the reproductive adaptations of angiosperms?

Answer 41

Flowers and fruits

Question 42

Which are the most widespread and diverse group of all plants?

Answer 42

The angiosperms; 90% of all terrestrial plants

Question 43

What is a flower?

Answer 43

A specialised shoot with up to four types of modified leaves (sporophylls) called floral organs for sexual reproduction

Question 44

What are the 4 types of modified leaves flowers can have?

Answer 44

1. Sepals – enclose the flower 2. Petals – brightly coloured, attract pollinators 3. Stamens – produce pollen 4. Carpels – produce ovaries

Question 45

Describe the modified leaves known as sepals

Answer 45

- Collectively called the calyx - Form the outermost part of the flower - Cover/protect the flower in bud - Often the most ‘leaf-like’ of the flower parts - Photosynthetic

Question 46

Describe the modified leaves known as petals

Answer 46

- Collectively called the corolla - Colourful - Attract pollinators

Question 47

Describe the modified leaves known as stamens

Answer 47

- Each composed of a filament that holds up a capsule like structure called an anther - Pollen grains, the immature male gametophytes, develop within the anther

Question 48

Describe the modified leaves known as carpels

Answer 48

- 'Container’ - Ovary: sac-like structure that contains one or more ovules, where female gametophytes develop - Style: long, slender neck of carpel where ovary is located - Stigma: sticky, moist tip which receives pollen

Question 49

Describe radial flower symmetry (eg Daffodil)

Answer 49

- Sepals, petals, stamens and carpels radiate out from a centre. - Any line through the central axis divides the flower into two equal parts

Question 50

Describe bilateral flower symmetry (eg Orchid)

Answer 50

Flower can only be divided into two equal parts by a single line

Question 51

Characteristics of fruit angiosperms

Answer 51

- Typically consist of a mature ovary but can also include other flower parts - Can be fleshy or dry - Can be carried by wind, water, animals to new locations

Question 52

Which two groups of angiosperms represent the vast majority of living angiosperm species?

Answer 52

The monocots and eudicots

Question 53

How can we distinguish monocots and eudicots based on their embryos?

Answer 53

Monocots have one cotyledon, eudicots have 2

Question 54

How can we distinguish monocots and eudicots based on their roots?

Answer 54

- The monocot root system is usually fibrous with no main root - Eudicots have a taproot where the main root is present

Question 55

What are Cotyledons?

Answer 55

The first part of a plant to emerge from the seed

Question 56

How can we distinguish monocots and eudicots based on their leaf ventilation?

Answer 56

- Monocot veins are usually parallel - Eudicot veins are netlike

Question 57

How can we distinguish monocots and eudicots based on their flowers?

Answer 57

- Monocot floral organs are usually in multiples of three - Eudicot floral organs are usually in multiples of 4 or 5

Question 58

What does angiosperm mean?

Answer 58

enclosed seeds

Question 59

When did angiosperms appear?

Answer 59

300 MYA

Question 60

What are floral organs?

Answer 60

Modified leaves

Question 61

What is the function of double fertilisation in angiosperms?

Answer 61

- One sperm fertilizes egg to form embryo (2n). - Second sperm fertilizes central cell to form nutritive endosperm (3n)

Question 62

Compare angiosperm and gymnosperm speed of reproduction

Answer 62

Angiosperms often have much faster reproduction than gymnosperms

Question 63

What are the evolutionary advantages of angiosperms?

Answer 63

- Coevolution with animals: Mutually beneficial relationships - Adaptability: Can thrive in almost all terrestrial environments

Question 64

What is the ecological and human significance of angiosperms?

Answer 64

- Ecological dominance - Food source - Ecosystem services: Oxygen production, carbon sequestration, soil stabilisation - Economic importance - Cultural significance

Question 65

What is the correct order of evolution? a) Green algae → Bryophytes → Seedless vascular plants → Gymnosperms → Angiosperms b) Bryophytes → Green algae → Seedless vascular plants → Angiosperms → Gymnosperms

Answer 65

A