Exam 1 Flashcards
When did life appear?
3.8 to 3.5 billion years ago
When did photosynthetic organisms appear?
3.8-3.5 bil
What are some of the evidence proving when cyanobacteria appeared?
- The ratio of 12C/13C in organic material is higher than in inorganic rocks
- Fossils dating to that time resemble structures formed by cyanobacteria
What of photosynthesis did ancestral cyanobacteria produce?
Water was not the electron donor and oxygen was not produced
When did oxygen-producing (oxygenic) photosynthesis appear?
3.5 bil years ago
What are the evidence of when oxygenic photosynthesis appeared?
Increase of the iron in soils due to the oxidation of Fe2+ t Fe3+ and the insolubility of this iron forming
What effect did oxygenic photosynthesis have on life?
- Increased oxygen concentration changed Earth’s atmosphere, enabling other living organisms via aerobic respiration
- Led to the formation of the ozone layer to protect from high wavelength UV/UV-C rays
- Fixed CO2 –> organic matter available to food for heterotrophs
When did eukaryotic organisms appear?
2.7 billion years ago
What led to the evolution of eukaryotes and photosynthetic bacterium?
Primary endosymbiosis event where a host cell mitochondrion engulfed a non-photosynthetic bacterium.
Later endosymbiosis with a host cell contained a mitochondrion engulfing another bacterium for it to turn into a chloroplast
What did the ancestral photosynthetic eukaryotes evolve into?
Glaucophytes (unicellular algae)
Rhodophytes (red algae)
Chlorophytes (green algae)
What did land plants evolve from and when?
Land plants evolved from green algae around 475-450 million years ago. Adapted to living on land not surrounded by water anymore
What do Charales and land plants have in common?
- Cellulose in the cell wall
- Formation of a phragmoplast during cell division
- Plasmodesmata
What are the major unifying traits of plants?
- primary producers converting solar to chemical energy, stored as carbohydrate bonds
- Sessile, growing towards resources as an adaptation
- structurally reinforced to compensate growth mass
- nutrients from soil and photosynthesis are transported using nonphotosynthetic movement mechanisms
- lose water continually via evaporation and have evolved to avoid dessication.
- embryos derive nutrients from mother plant, which facilitate self-supporting land structures.
What are the 5 key traits of land plants?
- apical meristems
- alternation of generations
- walled spores produced In sporangia
- multicellular gametangia
- Multicellular-dependant embryos
What characterizes a bryophyte?
These plants are nonvascular. In reproduction, the gametophytes are not dependent on the sporophytes. The gametophyte is dominant where the sporophyte is small and grows off the gametophyte as an extension.
What characterizes a tracheophyte?
These plants are vascular. The sporophyte is the dominant generation, where it grows off the tiny gametophyte.
What characterizes a seed plant such as a gymnosperm? What makes gymnosperms special?
Gametophytes are non-autotrophic. It contains male and female gametophytes where the sporophyte encloses the female gametophyte, and the male gametophyte is dispersed, such as in gymnosperms.
In gymnosperms, there are male and female cones which have a microspore and megaspore, respectively. The male cone produces pollen, containing the microspore which go to the female cone where the megaspore is. The megaspore acts as a womb where the seed is formed with the embyro
What characterizes angiosperms?
Angiosperms or flowering plants have flowers which attract pollinators.
The seed is enclosed in the fruit and gets dispersed by animals. A double fertilization even produces a diploid zygote as well as an 3n endospore, which provides nutrients to the embro/young plant.
What are the differences between monocots and dicots?
Monocots have parts and multiples in 3.
Dicots have flowers in parts of 4s or 5s, or multiples of those numbers.
When did angiosperms occur?
135-145 million years ago
Which plant types correspond to non-autotrophic gametophytes?
Gymnosperms and angiosperms
What plant structures derive from apical meristems?
leaves, flowers, roots, cambium…
In dicots, where is the secondary xylem produced, where does it grow towards? Is the secondary xylem closer or farther away from the cambium compared to the primary?
it is produced from the cambium and grows towards the pith. The secondary xylem is closer to the cambium than compared to the primary.
Vessel elements in the xylem are…
Specialized cells that are dead
What are the advantages of angiosperms?
- Animals help plants reproduce by bringing the pollen to the stigma
- Animals help disperse seeds via fruit-enclosed seeds
- Endosperm production gives nutrients for embryo until leaves grow
What is a diecious flower? Are all flowers diecious?
Diecious flowers mean male and female flowers are not on the same plant. Some plants, such as cucumber and maize corn, have male and female flowers on the same plant.
What are meristems?
Areas where plant growth is localized in areas where nuclear and cell division occurs. Undifferentiated cells divide via cell division and differentiation giving rise to the whole plant body.
What are the two primary meristem styles?
R.A.M (roots) give rise to the root cap and the rest of the root
S.A.M (shoots) give rise to all aerial parts of the plant (stem, branches, leaves, and flowers)
What does the primary meristem give rise to?
The primary meristem grows the plant in length through auxiliary buds, SAM, RAM, and lateral roots.
What is the secondary meristem and what does it grow?
found along the length of the root&shoot and grows the plant horizontally. Secondary growth continues on primary growth & makes plant thickers.
Contains the vascular cambium, cork cambium, intercalary cambium
What is the vascular cambium?
Produces wood.
Arises in the vascular system between the xylem and phloem of the primary plant body. Cells divide longitudinally producing derivatives toward inside and outside of the vasc. cambium of roots and shoots.
Cells inside also differentiate into secondary xylem and phloem.
What are the secondary xylem and phloem?
The secondary xylem is a product of the vascular cambium, which conducts water and nutrients to organs and is characterized by thick secondary walls. Becomes annual rings. Xylem divides towards the inside.
The secondary phloem conducts photosynthesis products to the reproductive organs or downwards to other organs. Divides towards outside
What is the cork cambium?
Produces the protective periderm consisting of waterproof cells.
The cork plus cork cambium plus the secondary phloem consists of bark.
What are intercalary meristems?
Primary meristems located at the nodes allow grasses to grow even after it is cut.
What is the epidermis?
The epidermis is the outermost layer of cells in plant organs. It includes specialized cell types such as root hairs, guard cells, trichomes, and secretory cells
In older cells, it is sloughed off and replaced by periderm.
What are guard cells?
Guard cells open/close the stomata area and must be monitored so evaporation and co2 movement can be regulated
What are ground tissues>
Ground tissues contains pith, cortex, mesophyll and leaf cells. It is the bulk of the plant. It also includes
Parenchyma, collenchyma and sclerenchyma cells
What are parenchyma cells?
Parenchyma cells are the most abundant type of specialized ground tissue cells. They are present in all parts of the plant. They are spherical and can differentiate into various other ground and vascular tissues after production. They function primarily for food, water storage or photosynthesis.
What are collenchyma?
Collenchyma are thick primary walls that continually elongate. They lie right beneath the epidermis and function as flexible support for organelles.