3.2 Flashcards
What are the characteristics of Eukaryotes?
Most are larger than bacteria and archaea, have membranous organelles, and a cytoskeleton. DNA is in a nucleus that is surrounded by a membrane. Only eukaryotes can be multicellular
What are membranes for eukaryotes?
Synapomorphy, they all have it
What are the properties of simple multicellular organisms?
Adjacent cells stick together via adhesion molecules. Little to no communication or transfer of resources. Little differentiation, most or all cells retain range of functions including reproduction. Every cell is in contact with external environment.
What do all complex multicellular organisms have?
Cell communication and transfer of materials. Differentiation. 3 dimensional structures resulting in cells not in direct contact with the environment
What happens as multicellular organisms get larger?
They have more interior cells that are not in contact with the environment
What are the two mechanisms that transport materials in multicellular organisms?
Diffusion and osmosis, and bulk transport
What is diffusion?
The random motion of molecules, net movement of areas with higher concentration to lower
What is bulk transport?
Any means by which molecules move through organisms at rates faster than diffusion
When is diffusion effective?
Small distances
Why are some plants that use diffusion small?
Diffusion limits the size and shape of organisms so that they can stay in close contact with the environment
True or false: There are organisms that have the cells that require resources near their exterior but have larger interior made up of inactive tissue
True, they do exist
What happened as complex organism became larger?
Evolution of specialized transport systems for bulk transport enabled the movement of molecules faster across larger distances unlike diffusion
How many times did complex multicellularity evolve in eukaryotic groups?
6 times
What are the groups where complex multicellularity evolved?
Animals, Green algae that are ancestors of land plants, red algae, brown algae, and fungi twice
Which 3 groups have complex multicellularity?
Fungi, land plants, and animals
What are protist?
Other eukaryote groups with complex multicellularity scattered among the remaining taxa
What are two characteristics of protists?
Can be single celled, or have simple/complex multicellularity. All live in some kind of watery environment
What are some photosynthetic protist?
Algae
Which algae groups gave ride to land plants?
Green algae
What distinguishes all land plants from green algae?
Evolution of water-proof cuticle and pores/stomata. Fertilized egg develops into a multicellular embryo which attached to parents and is protected by them and nourished
What does a cuticle do?
Prevents water loss from organism
What do pores/stomata do?
Allow gas exchange in photosynthetic tissue
What are the benefits to living on land?
More space, sunlight, and CO2 for photosynthesis
What are the four major transformations in LIFE CYCLE and STRUCTURE characterize the evolutionary history of plants?
The evolution of alternation of generations
The evolution of vascular plants
The evolution of pollen and seeds
The evolution of the flowers and fruits
What is the first major transformation?
Alternation of generations
What two forms do every plant species alternate between?
Haploid gametophyte generation that makes gametes, a diploid sporophyte generation that makes spores
How does alternation of generation benefit plants?
Plants can shift between forms that increase variability and are specialized for fertilization, and forms that increase production and are specialized for dispersal
What must happen with the gametes from the haploid gametophyte generation?
They must recombine to form new individuals which leads to variability
Where did gametophyte evolve and why?
Low to the ground, it can release swimming sperm into the surface layer enhancing fertilization
What do the diploid sporophyte generation produce and with what phase?
Different spores by meiosis
Why is it important to make different spores from diploid sporophyte generations?
The spores disperse through the air and give plants and advantage in colonizing
Where do sporophyte evolve and why?
Taller than gametophyte to produce spores at tip that can easily be carried by the air to different locations
How are light nutrients water and CO2 challenges on land?
The resources are in different locations.
Where do land plants get water and soil nutrients?
Below the ground
Where do land plants get light and CO2?
Above ground
Where do land plants get oxygen?
Above and below ground