Flashcards in Plants Deck (58)
What is biodiversity?
The variety of life, in all its manifestations. It encompasses all forms, levels and combinations of natural variation.
How much biomass - excluding microbes - do plants represent?
What do Plants provide for humans?
Feed us, provide drugs, materials for clothing and building, one of our main sources of fuel - living and dead
For how much of Earths history was the land face largely lifeless?
When did plants begin to colonise land?
When did plants evolve to grow tall, leading to the first forests?
How many known plant species are there?
How do plants enable other forms to exist successfully on land?
Roots provide habitats by anchoring the soil, supply oxygen and provide food for terrestrial
What key characterises are shared by plants and protists?
multicellular eukaryotes, photosynthetic autotrophs
What else, other than plants have cell walls made of cellulose?
Green algae - charophytes and dinoflagellates
What are charophytes?
Division of freshwater green algae, possibly closest relative to land plants.
What similarities to charophytes and green algae share?
Rosette shaped cellulose, Peroxisome enzymes, Formation of phragmoplast, Structure of flagellated sperm
How are protein arrays arranged in non charophyte algae?
Describe what is meant by Rosette shaped cellulose
Cells have circular petal shaped arrays of protein on the plasma membrane, which synthesise cellulose microfibrils
What is the phragomplast?
Mechanism in plant and charophyte cell division, forms during late cytokinesis, a group of microtubules that form between the dividing nuclei acts as a scaffold for forming cell plate
Where do charophytes live?
shallow waters at the edge of ponds and lakes
How did natural selection in the habitat of charophytes lead to the evolution of land plats?
Live in habitats that may dry out, so selection favours plants that can withstand long periods out of the water.
What feature do charophytes have to protect their zygote when dry?
Strong sporopollenin walls
What are the benefits of moving onto land?
Bright, unfiltered sunlight, more plentiful CO2, soil rich in minerals and nutrients, relatively few herbivores
What were the physiological problems did plants have to overcome moving onto land?
Water balance, Availability of essential nutrients and gases, Support, UV protection, reproductive strategy
How did plants adapt to limited water availability on land?
No longer bathed in water, had to use rhizoids/Roots, xylem, cuticle and stomata
How did plants adapt to obtain nutrients and gases on land?
Collect from soil and atmosphere using roots and stomata
How did plants adapt to support on land?
use lignified conducting tissues
How did plants adapt to UV protection on land?
use of a cuticle
How did plants adapt their reproductive strategy for life on land?
protected by sporopollenin, dispersal by new vectors
What are the derived traits shared by plants?
Alternation of generations and multicellular dependent embryo
Walled spores produced in Sporangia
What is alteration of generations?
Lifecycle alternates between multicellular haploid organisms and multicellular haploid organisms, each generation gives rise to the other
What is the diploid generation called?
What is the haploid generation called?