Plant Diversity

Question 1

What are charophytes the closest relative of

Answer 1

land plant (embryophyte)

Question 2

4 key traits of land plants that are absent in green algae charophytes

Answer 2

• alternation of generations (multicellular, dependent embryos) - life cycle of plants
• walled spores produced in sporangia
• multicellular gametangia
• apical meristems: growth region in plants found within root tips and tips of new shoots and leaves

Question 3

Sporangia

Answer 3

organ where sporophyte produces spores

Question 4

Sporocytes

Answer 4

• diploid cells
• undergo meiosis to generate haploid spores

Question 5

Sporopollenin

Answer 5

• contained in spore walls
• protect against dessication making them resistant to harsh environments

Question 6

Archegonia

Answer 6

• female gametangia
• produce eggs and are the site of fertilization

Question 7

Antheridia

Answer 7

• male gametangia
• the site of sperm production and release

Question 8

Life cycles of non-vascular plants

Answer 8

• spore germinates into a gametophyte
• mature gametophytes produce flagellated sperm in antheridia and an egg in each archegonium
• sperm swim through a film of water to reach and fertilize the egg
• diploid zygote develops within archegonium, becomes an embryo via mitosis
• embryo will give rise to the diploid sporophyte
• sporophyte will produce spores which will be contained within the sporangia

Question 9

Life cycles of seedless vascular plants

Answer 9

• sporophyte generation is the dominant and photosynthetic part of the life cycle
  -underneath the sporophylls of sporophyte there are sporangia present
  -spores will develop into the haploid gametophyte
• in ferns the gametophytes are hermaphroditic
• need water for flagellated sperm to swim from antheridia and into archegonia for purposes of fertilizing egg
• fertilized egg becomes diploid zygote, gives rise to the diploid sporophyte

Question 10

Sporophyll

Answer 10

spore bearing leaves
- underneath them there are sporangia present

Question 11

Sorus

Answer 11

group of sporangium

Question 12

4 common characteristics to all seeded vascular plants

Answer 12

• reduced gametophytes
• heterospory
• ovules
• pollen

Question 13

Reduced gametophytes

Answer 13

• mosses and other bryophytes have life cycles dominated by gametophytes
• ferns and other seedless vascular plants have sporophyte-dominated life cycles
• continued in the vascular plant lineage that led to seed plants
• miniaturization allowed for an important evolutionary innovation in seed vascular plants
• tiny gametophytes can develop from spores within the sporangia of the parental sporophyte
• protects gametophyte from environmental stress

Question 14

Homosporous

Answer 14

• non-vascular and most seedless vascular plants
• produce one type of spore of the same size

Question 15

Heterosporous

Answer 15

• seed vascular plants
• produce spores of 2 different sizes and sexes by the sporophytes

Question 16

Ovule

Answer 16

immature seed

Question 17

Seed

Answer 17

fertilized ovule

Question 18

Megasporangium/nucellus (diploid)

Answer 18

• produce megaspores that give rise to female gametophytes
• inner cell mass of ovule, comprising of diploid sporophytic cells

Question 19

Megasporocyte (diploid)

Answer 19

• diploid cell that undergoes meiosis to produce four haploid megaspores
• at least one of the spores develops into the haploid female gametophyte

Question 20

Megaspore (haploid)

Answer 20

• develop into female gametophytes within the ovule, where fertilization takes place, leading to the formation of seeds

Question 21

Integument

Answer 21

• layer of sporophyte tissue (diploid) that envelops and protects the megasporangium and the megaspore
• develop into the seed coat when the ovule matures after fertilization
  angiosperms have 2 - covered by ovary wall
  gymnosperms have 1- uncovered

Question 22

3 components that a mature seed contains

Answer 22

• the diploid integument which develops into the seed coat
• the haploid female gametophyte (food supply)
• the diploid embryo (will germinate to become a new sporophyte)

Question 23

Microsporangium (diploid)

Answer 23

-produce microspores that give rise to male gametophytes
- pollen sac that contain microsporocytes

Question 24

Microsporocytes (diploid)

Answer 24

• a diploid cell that undergoes meiosis to produce 4 haploid microspores
• each microspore will ultimately form a haploid pollen grain (male gametophyte)

Question 25

Microspores (haploid)

Answer 25

• each microspore will ultimately form a haploid pollen grain (male gametophyte)

Question 26

Life cycle of plants

Answer 26

-multicellular gametophyte (haploid) produces haploid gametes by mitosis
-fusion of gametes results in fertilization, rise to the diploid zygote
- zygote divides by mitosis, develops into a multicellular diploid sporophyte
- sporophyte produces haploid spores by meiosis
- spores divide by mitosis and develop into the gametophyte

Question 27

Similarities and differences between zygotes and spores

Answer 27

similarities - both single cells that divide by mitosis to form a multicellular individual
difference - zygotes result from the fusion of two cells such as sperm and an egg (diploid)
- spores are not formed by fusion of 2 cells (haploid)
- zygotes produces sporophytes
- spores produce gametophytes

Question 28

Apical Meristems

Answer 28

• comprise of embryonic cells and are the growth regions at plant tips (root tips and shoot tips) allowing plants to sustain continual growth in their length

Question 28

Bryophytes

Answer 28

• non-vascular
  ex. liverworts, hornworts, mosses
• gametophytes are dominant part of the life cycle

Question 28

Vascular tissue

Answer 28

• xylem and phloem
• allows vascular plants to grow tall compared to the non-vascular plants