Theme 3 Plants Flashcards
What is an organisms phenotype dependent on?
cell number, type, and function
Does every cell in an organism have an identical genome?
Yes, they all have identical DNA sequences
What are the two major endosymbiotic events in life?
The acquisition of mitochondria and the acquisition of plastids.
Do all organisms have a common unicellular ancestor?
Yes
How long ago was the plant-animal eukaryotic ancestor formed.
1.6 Ga
When were multicellular trace fossils found?
0.6 Ga
Why do we classify organisms?
To understand similarity and diversity of living organisms in an organized manner, provides information on evolutionary lineages
What is a potential application for understanding evolutionary lineages?
Fruit flys, they are very similar to us evolutionary wise and therefore can be used as a model organism in order to study diseases in humans
What are the defining characteristics of land plants?
Eukaryotes
Almost all are photoautotrophs
Multicellular
Sessile or stationary (because its photosynthetic and rooted)
Cell walls
Alternation of generations life cycle
Embryo (sporophyte (diploid)) retained on the gametophyte (haploid) tissue
Name a heterotrophic plant, how do we know it’s a plant without identifier of chloroplast?
Monotropa uniflora, is a parasitic plant that gets organic carbon from other plants. Can grow in dark conditions as long as they have a source of carbon.
What is the primary cell wall?
All plants have this, is a cell wall that surrounds plasma membrane and cell contents (cytoplasm, organelles).
Is flexible, can move and expand to increase cell length.
What is the primary cell wall made out of?
Made from sheets of cellulose fibres in a matrix of hemicellulose, include sugars and structural proteins (Pic on slide 17).
Is the plant cell wall a good source of nutrients?
No, as it is primarily made of cellulose, which is a compound humans don’t have the enzymes to digest, it goes straight through our digestive systems.
Can cellulose be used as a fuel source?
No as you need to break it down to make biofuels, needs a very high temp which is too costly for this fuel source.
Name an example of cellulose?
Pure cotton
What type of plant cell have a secondary cell wall?
Xylem and sclerenchyma are types of plant cells that have a secondary cell wall.
What is the difference between the primary cell wall and secondary cell wall?
Difference between primary and secondary cell wall is that the secondary cell wall has it’s cellulose fibres anchored with lignin which makes it more strong, more rigid, and creates a waterproof barrier.
Do plant cell walls themselves provide ridgitiy?
No, It is not the cell wall but the turgor pressure from the vacuole pushing against the cell wall that provides rigidity
How does turgor pressure work in plant cells?
Plant cells main features that contribute to turgor pressure are the cell wall, the vacuole, and the tonoplast- a membrane that surrounds the central vacuole.
Plant cells acquire or lose water through osmosis, vacuoles have high solute concentration (less water) which induces water to flow into the vacuole from outside the cell, this enlarges the vacuole which pushes against the tonoplast and then causes the tonoplast (plasma membrane) to enlarge and push against the cell wall. This creates rigid cells, and is called turgid pressure.
What are the three states of cells in osmosis, and what are the corresponding plant cell states?
Hypertonic - Plasmolyzed
Isotonic- Flaccid
Hypotonic- Turgid
What happens when plant cells are hyptonic?
Plant cells are turgid, water rushes into vacuole as there is a lower concentration of water inside the vacuole than outside the plant cell- usually cells would burst but plant cells don’t because cell wall provide support. This is what we would expect in a well watered plant.
What happens when plant cells are isotonic?
Water concentration inside vacuole is equivalent to outside of vacuole, as vacuole doesn’t swell up, tonoplast doesn’t press up against cell walls, leading to less turgid pressure and therefore a flaccid plant.
What happens when plant cells are hypertonic?
Water concentration outside plant cell is less than in the vacuole, water rushes out of vacuole (shrinking it and tonoplast) and the cells of the plant become plasmolyzed. The plant is now dead, this happens when their is no water in the soil of a plant.
Whats a specific example of a plant that utilizes turgid pressure? Describe how they do it?
Touch me nots, when touched release chemicals that cause water to rush out of vacuole. This is why they shrink away.
What does alternation of generations mean?
Plants alternate between a haploid (gametophyte) and a diploid (sporophyte) generation during a single life cycle.
How is plant life cycle different from animals?
Animals have a free living (not dependent on other organism) diploid (dominant) individual (parent), form their gametes (haploid, unicellular) through meiosis, and these gametes are not free living- need diploid individual for survival.
In plants- Dominance of diploid (sporophytic) and haploid (gametophytic) stages alter and vary for different groups of plants.
Gametophyte are multicellular produced through mitosis from unicellular spores. Go through mitosis to produce a lot of gametes (unicellular)
A lot more gametes are produced- chances of successful reproduction higher.
Describe life cycle for plants starting from sporophyte- list each stage as n, 2n, and uni or multiceullular
Sporophyte 2n, multicellular plant structure.
Produces spores (n) unicellular through meiosis.
Spores (n, unicellular) produce gametophyte (plant structure) (n, multicellular) through mitosis.
Gametophyte (n, multicellular) goes through mitosis to produce n, unicellular gametes.
Gametes go through fertilization produce diploid unicellular zygotes and 2n multicellular offspring.
Where does the embryo go following fertilization?
The embryo is retained on the female gametophyte inside the tissue
What are the two things land plants are classified froms?
Presence of
-vascular tissue
-seeds
What is a vascular system?
Is the circulatory system/network that addresses the plants water and nutrient needs. Can see vascular tissue on plant (veins).
What are vascular bundles?
Is vasculature tissue but occur in bundles together. Is a component of the vascular system.
What are the 4 cell types in vascular bundles? What do they do?
Xylem (are water conducting cells, dead at maturity)- have secondary cell wall, provide structural support
phloem (are cells that transport sugars and other solutes, alive at maturity)
parenchyma cells
and fiber cells- are sclerenchyma cells- have secondary cell wall, provides rigid support to xylem and phloem. Have files of it running through the vascular system.
What are industrial uses of fiber cells?
Strong fiber cells provide raw material for:
textile industry (linen from flask)
Rope (get this from hemp/cannabis)
What is lignin?
Lignin is the second most abundant polymer after cellulose. It is hydrophobic and aromatic in nature. It is co-valently linked with cell wall polysaccharides (hemicellulose) providing the rigidity and strength for the cell wall.
Why are vegetables crunchy and fiberous?
crunchy and fiberous due to lignin in xylem and sclerenchyma.
What is the greatest advantage of having vasculature?
Allows you to stand tall and therefore look for sunlight, increases photosynthetic capacity- this is what allowed trees to dominate.
Describe the transport routes in plants
Water and solute enter plant roots through plasma membrane of root hair (short distance transport)
Water and mineral ions travel from root into xylem cells by passing through or between plant cells.
Vascular system distributes water through out the plant through xylem cells, exits plant through leaves.
Sugars get distributed through plant by being loaded in and out phloem starting from leaves until they reach the roots.
Label three parts of seed on slide 30
- Cotyledon, 2 true leaves, 3 radicle or roots
Are hornworts closer to lycophytes or bryophytes genetically
Lycophytes
What are naked seeds? which type of plant has them?
Naked seeds are seed not enclosed in an ovary, gymnosperms have these.
Name characteristics and examples of nonvascular plants
Lack vascular tissue
Haploid generation is dominant
Bryophytes (eg. Mosses)
Diploid generation small/shorter time
Bryophytes- liverworts, mosses, hornworts