Intro Flashcards
How old is the earth and when we’re the first fossils
4.6x10^9
3.5 Ga (1Ga=10^9 years)
The first organisms were heterotrophs or autotrophs?
Heterotrophs
Stromatolites
Earliest fossils: microbial mats made of layers of microorganisms and sediment. Similar to modern stromatolites formed by Cyanobacteria
How did photosynthesis alter earths atmosphere
-oxygen released from photosynthesis into oceans and lakes reacted with dissolved iron and precipitated as iron oxides
-2.7-2.2 Ga gradual accumulation in the atmosphere leading to the great oxidation event
-700Ma ago, marked increase in levels of atmospheric oxygen
What time period approached modern oxygen levels and when
Cambrian (570-510 Ma)
Cyanobacteria
Photosynthetic bacteria
Anoxygenic
Photosynthesis but no oxygen is produced
Protobacteria and chloroflexi
What type of photosynethis do Cyanobacteria undergo
Photo systems 1 and 2
Need sun, water and carbon dioxide, and release oxygen
Consequences of great oxidation event
- Ozone later formed 450 Ma making life possible near water surface and land
- Free oxygen (lethal to some organisms, important selective pressure, possible acceptor of elections in cellular respiration)
- Evolution of eukaryotic cells-2.1Ga ago
Aerobic respiration give more _____ in cellular respiration
ATP
Due to oxygen being a good carrier of electrons
Heterotroph
Dependent on an outside source of organic molecules for its energy.
-animals, fungi, one cell organisms
Autotrophs
Able to make own energy-rich molecules out of simple inorganic materials.
Prokaryotic
Eukaryotic
No nuclear envelope or chromosomes
Nuclear envelopes, complex chromosomes, organelles surrounded by membranes (all but bacteria and archea)
Epidermis and cuticle of plants
Outermost layer of cells, of all above ground portions of the plant involved in photosynthesis. Also epidermis on roots.
Waxy layer preventing water loss
Stomata
Paired with guard epidermal cells around them; is a small opening from the epidermis of a plant.
-open and close in response to environmental and physiological signals to maintain water and gas balance
Annuals
Perennials
Stem differences
Plants with a life span of one year. Stem is photosynthetic organ too
Longer living plants. Stem may become thickened and woody and covered with cork which prevents water loss.
Xylem and phloem
Parts of a plants vascular/ conducting system.
Through which water passes upward through the plant body
Through which food manufactured in the leaves and other photosynthetic parts is transported throughout the plant.
Meristems
Where plant growth originates
Embryonic tissue regions capable of adding cells indefinitely to the plant body.
Types of meristems
Apical-meristems located at the tips of all roots and shoots. Involved with extension of the plant body. (Primary growth)
Lateral-meristems-growth resulting in thickening if stems and roots in secondary growth. Two types of lateral meristems: vascular cambium and cork cambium
During transition to air, plants underwent which adaptation to reproduce?
-production of drought resistant spores
-complex, multicellular structures in which gametes were held and protected from drying out by a layer of sterile cells.