Plant Biology Notes
Sophomores Editions: Introduction to Plants
What is a Plant?
Biologically, how would you correctly describe plants?
Examples of Plants
Cyanobacteria
Brown algae
Liverworts
Green algae
Red algae
Relative Absorption
Diagram showing relative absorption (percent) across different wavelengths of light (nanometers) for various pigments:
Carotin
Phaeophytin
Chlorophyll a
Chlorophyll b
Lutein
Vidaxanthin
Neoxanthin
Carotenoids
Phycocyanin
Phycoerythrin
The electromagnetic spectrum is displayed with wavelengths ranging from gamma rays to radio waves.
Visible light ranges from 380 nm to 750 nm.
Chlorophyll a, chlorophyll b, chld, and chlf absorption spectra are shown on a graph with wavelength on the x-axis and absorption on the y-axis.
Key characteristics of plants:
Eukaryotes
Cell walls of cellulose
Photosynthesis using chlorophyll a & b
What Plants Need to Survive
Sunlight
Carbon dioxide
Water
Oxygen
Sugars
Activity: Plant Trait Sorting
Sort plants into 5 groups.
Name the trait of each group (+ optional: individual's names).
Put 5 clusters into evolution order (according to these traits).
Present your view on the history and key events of plants.
Examples of traits to consider:
Leaf size and structure
Texture
Height
Stem thickness
Presence of cones or spore cases
Color
Need for water
Flowers
Fruits
Seed type
Evolutionary Milestones
Evolutionary milestones marked with time scales: 93m, 96m, 120, 115m, 90, 60, 30, 25m.
Brainstorming Benefits of Milestones
What innovation (how opposed the obstacle?)
Compare to the life of “older” species without SUCH A Trait
Evolutionary Timeline
Timeline of Plant Evolution:
Ordovician
Silurian
Devonian
Carboniferous
Key Groups/Events:
Coleochaetales
Charales
Marchantiopsida
Anthocerotopsida
Bryopsida
Eoembryophytic
Embryophytes (terrestrialization)
Eotracheophytic
Agalophyton
Rhyniopsida
Polysporangiophytes
Tracheophytes
Eutracheophytic
Drepanophycales
Lycopodiaceae
Lycophytina
Protolepidodendrales
Selaginellales
Isoetales
Zosterophyllopsida
Psilophyton
Sphenopsids
Euphyllophytina
Ferns
Seed plants
The Risk of Terrestrialization
"Plants 'risked death' stepping onto dry land."
Identifying Plant Groups
What are 4 most important traits by which we identify Plant Groups?
Plant ancestor
Flowers
Seeds
Seeds enclosed in something.
Challenges on Land
On land, plants face new deadly problems.
Stomatal Density and Photosynthetic Efficiency
Questions related to stomatal density:
Describe the evolutionary trend in stomatal density and propose a hypothesis that explains this trend.
Design an experiment to test whether increased stomatal density improves photosynthetic efficiency in land plants.
Identify one other structural adaptation besides stomata that supports life on land and explain how it contributes to terrestrial success.
Leaf Structure
Diagram of leaf structure:
Cuticle
Upper epidermis
Mesophyll (palisade and spongy)
Lower epidermis
Guard cell
Stoma
Chloroplast
Vacuole
Nucleus
Cell wall
Cytoplasm
Plant Life Cycle
The life cycle of land plants has two alternating phases, a diploid phase and a haploid phase.
Alternation of Generations - Questions
Haploid spores are produced by the [ sporophyte / gametophyte ]
A zygote is produced by the fusion of [ gametophytes / gametes ]
Spores reproduce by [ meiosis / mitosis ] to produce a gametophyte.
Sporophytes are [ diploid / haploid.] Gametophytes are [ diploid / haploid.]
A zygote is [ diploid / haploid.] . A spore is [ diploid / haploid.]
Sporophytes and gametophytes are both produced through the process of [ meiosis / mitosis ]
Which of the following is the best description of the process of alternation of generations? (Check all that apply)
__ a life cycle that includes a unicellular haploid stage
__ a life cycle that includes a unicellular diploid stage
__ a life cycle that includes a multicellular diploid stage
__ a life cycle that includes a multicellular haploid stage
Trend in Alternation of Generations
*Describe the trend in alternation of generations during evolution of plants and: Tell me why!
Diagram showing the alternation of generations in different plant groups:
Green Algae
Mosses and Relatives
Ferns and Relatives
Seed Plants
Relative size and life span of gametophyte and sporophyte in:
GREEN ALGAE
BRYOPHYTE
FERN
GYMNOSPERM
ANGIOSPERM
Localization of the TP53 Gene
Image showing the localization of the TP53 gene on chromosome 17 at location 17p13.1
Green Algae
1st group of PLANTS (not a true land plants)
What is Algae?
Explanation of "ALGA"
Multicellularity
Introduction to multicellularity
Specialization in Algae
Specialization (no true organs)
Genetic modulation of cell number
Cell-cell attachments
Organismal polarity
Examples of algae and their developmental complexity:
Chlamydomonas reinhardtii
Tetrabaena socialis
Gonium
Pandorina morum
Eudorina elegans
Pleodorina starrii
Volvox carteri
Examples of Algae
Chara
Volvox america
Spirogyra
Example of Spirogyra
Green Algae and Plant Evolution
Green Algae gave rise to plants
Algae Habitats
Where do algae live?
Fresh or Saline?
Dependent on aquatic environment
Algae Life Cycle and Structure
How does a life of a common ALGAE look like:
*Describe life cycle & structure
Chlamydomonas Life Cycle
Example: Algae called Chlamydomonas can switch between HAPLOID and DIPLOID phase
Diagram of Chlamydomonas life cycle:
Haploid (N) phase with asexual reproduction (mitosis) and production of zoospores.
Diploid (2N) phase with sexual reproduction, pairing of gametes, and formation of a zygote.
Release of haploid cells.
Preferred Phase of Algae
Which phase do they prefer more?
Haploid (N) is usually preferred
Reasons for Switching to Sexual Reproduction
e.g. Chlamydomonas usually divides asexually by mitosis. Tell me, what can be the reason for switching into Sexual Reproduction?
Meiosis
Mitosis
Nitosis
Asexual Reproduction and New Variants
Can I produce new variants by ASEXUAL REPRODUCTION by mitosis?
Sexual Reproduction in Algae
*Normally green algae lack multicellular sporophyte
Why is it better to choose Sexual Reproduction?
Okay, let's go through the questions from the presentation:
Biologically, how would you correctly describe plants?
Eukaryotes with cell walls of cellulose that perform photosynthesis using chlorophyll a & b.
Sort plants into 5 groups. Name the trait of each group (+ optional: individual's names). Put 5 clusters into evolution order (according to these traits). Present your view on the history and key events of plants. Examples of traits to consider: Leaf size and structure, Texture, Height, Stem thickness, Presence of cones or spore cases, Color, Need for water, Flowers, Fruits, Seed type.
This is an activity question, so the answer would depend on the specific traits and groupings chosen during the activity.
What innovation (how opposed the obstacle?)
This question is related to brainstorming the benefits of evolutionary milestones, so the answers would vary depending on the specific milestone being discussed.
Compare to the life of “older” species without SUCH A Trait
This question is related to brainstorming the benefits of evolutionary milestones, so the answers would vary depending on the specific milestone being discussed.
What are 4 most important traits by which we identify Plant Groups?
Plant ancestor, Flowers, Seeds, Seeds enclosed in something.
Describe the evolutionary trend in stomatal density and propose a hypothesis that explains this trend. Design an experiment to test whether increased stomatal density improves photosynthetic efficiency in land plants. Identify one other structural adaptation besides stomata that supports life on land and explain how it contributes to terrestrial success.
These are open-ended questions designed to encourage further thought.
Haploid spores are produced by the [ sporophyte / gametophyte ]
gametophyte
A zygote is produced by the fusion of [ gametophytes / gametes ]
gametes
Spores reproduce by [ meiosis / mitosis ] to produce a gametophyte.
mitosis
Sporophytes are [ diploid / haploid.] Gametophytes are [ diploid / haploid.]
diploid / haploid
A zygote is [ diploid / haploid.] . A spore is [ diploid / haploid.]
diploid / haploid
Sporophytes and gametophytes are both produced through the process of [ meiosis / mitosis ]
mitosis
Which of the following is the best description of the process of alternation of generations? (Check all that apply)
a life cycle that includes a multicellular diploid stage
a life cycle that includes a multicellular haploid stage
Describe the trend in alternation of generations during evolution of plants and: Tell me why!
This is an open-ended question designed to encourage further thought.
Where do algae live?
Fresh or Saline? Dependent on aquatic environment
How does a life of a common ALGAE look like: [*]Describe life cycle & structure
This is an open-ended question designed to encourage further thought.
Which phase do they prefer more?
Haploid (N) is usually preferred
e.g. Chlamydomonas usually divides asexually by mitosis. Tell me, what can be the reason for switching into Sexual Reproduction?
Meiosis
Can I produce new variants by ASEXUAL REPRODUCTION by mitosis?
No.
Why is it better to choose Sexual Reproduction?
Normally green algae lack multicellular sporophyte, and there are a variety of other reasons to choose it as well.