INTRODUCTION TO PLANT DEVELOPMENT

Question 1

Plant model organism

Family

Answer 1

Arabidopsis thaliana

Brassicaceae

Question 2

Attributes of A. thaliana as a Model System: (Brassicaceae) (7)

Answer 2

Small size

Shorter generation time

Large progeny for genetic analysis

Small genome size (125 MB) - completely sequenced

Small number of chromosomes (n=5)

Amenable to transformation

Spectrum of genetic and molecular resources

Question 3

People:

First discovered by ___ in the Harz mountains but he called it ___

____ summarized the potential of A.thaliana for genetics

____ collected the first mutant

Answer 3

Johannes Thal
Pilosella siliquosa

Friedrich Laibach

Reinholz

Question 4

Dates:

_____ F. Laibach first summarized the potential of Arabidopsis thaliana as a model organisms for genetics

______Correct chromosome number was published

_____Collection of first mutant by Reinholz

______Use of Arabidopsis in laboratory studies

______Whole genome was sequenced

Answer 4

1943
1907
1947
1970
2000

Question 5

Botanists that recognized that all terrestrial plants alternate between haploid gametophyte and diploid sporophyte (2)

Answer 5

Hofmeister
Starsburger

Question 6

Advantages of the Alternation of Generation in Plants (4)

Answer 6

Genetic Diversity: The alternation of generations increases genetic variation through sexual reproduction, which can enhance the adaptability and survival of plant species in changing environments.

Adaptation to Different Environments: The alternation between haploid and diploid stages allows plants to exploit different ecological niches. For example, the gametophyte may be better suited for certain environments than the sporophyte.

Increased Survival Rates: Producing spores and seeds can enhance survival rates by allowing plants to disperse widely and colonize new areas, reducing competition for resources.

Specialization of Functions: Different generations can specialize in different functions, such as nutrient acquisition in one stage and reproduction in another, optimizing overall plant fitness.

Question 7

Disadvantages of the Alternation of Generation in Plants

Answer 7

Complex Life Cycle: The alternation of generations involves a more complex life cycle compared to plants that reproduce solely through vegetative means, requiring more energy and resources to complete each stage.

Dependence on External Factors: Some stages in the life cycle, such as the gametophyte stage, may be highly dependent on specific environmental conditions, making plants vulnerable to environmental changes.

Reproductive Barriers: The need for specific conditions for fertilization and spore development can limit the reproductive success of plants in certain environments.

Question 8

Reproductive Barriers in Plants:

Prezygotic barriers (4)

Postzygotic barriers (1) (3)

Answer 8

Prezygotic barriers:

Niche Differentiation (Ecogeographic Isolation)
Phenological Isolation (time difference)
Pollinator Specialization (different floral traits)
Pollen-Stigma Interactions & Pollen Competition

Postzygotic barriers:
Extrinsic (hybrid cannot grow where parent is)
Hybrid sterility
Hybrid seed lethality
Hybrid Inviability