Packet 13: Plants Chapters 21-24

What are the characteristics of a Plant? Multicellular - which means they are made up of many cells Eukaryotic - which means cells are more complex & contain a nucleus Have cell walls made of cellulose -, a large carbohydrate Autotrophs - that undergo photosynthesis (they make their own food). Must have sunlight, water & minerals, and be able to exchange gases with the atmosphere.

Early Plants: Before the existence of plants, organisms got most of their oxygen from algae and photosynthetic prokaryotes (bacteria). Plants are thought to have evolved from algae (an aquatic plant-like protist)

Photosynthesis The food making process used by plants , algae & some prokaryotes, which supports life on earth Mainly occurs in specialized cells of the leaf. Equation: Carbon Dioxide + Water + Solar Energy  Glucose + Oxygen 6CO2 + 6H2O + Solar energy  C6H12O6 + 6O2

Cell Respiration: The process by which energy in food is changed into a usable form of cell energy (called ATP). Cell Respiration is almost the reverse of photosynthesis. Equation: Glucose + Oxygen  Carbon Dioxide + Water + ATP C6H12O6 + 6O2  6CO2 + 6H2O + ATP

Evolution of Plants (the order that they appeared on Earth) 1st - Nonvascular, seedless plants 2nd - Vascular seedless  3rd - Vascular seed plants…without flowers & fruit  4th - Vascular seed plants…with flowers & fruit

Terms to Know: Nonvascular plants – do not have tubes or vessels to move water and dissolved minerals up away from the ground and therefore have to rely on osmosis. This limits the height of these plants. The only plant on the cladogram that is a nonvascular plant is the Moss

Vascular plants – contain two kinds of vascular tissue: xylem (which transports water up) & phloem (which transports food down & up).

Because of their vascular tissue, vascular plants are able to: Grow taller b/c they can transport things upwards (against the pull of gravity). have true: roots (used for absorbing water and minerals from soil, anchors plant to the ground & stores food) stems (used for support; letting the plant grow toward the sun) & leaves (used for trapping light & site of photosynthesis) In the cladogram, the vascular plants include: ferns, cone-bearing plants (gymnosperm) and flowering plants (angiosperm).

Seedless Plants – must have water for reproduction so that the sperm can travel to fertilize the egg. This limits the environment that plants can survive and reproduce in. Example: Ferns

Seed Plants – enabled reproduction without water because seeds provide protection for the plant embryo. Seed plants are divided into two groups:

Gymnosperms – bear seeds on the surface of cones, which is why the largest group of gymnosperms is called conifers.

Angiosperms (aka flowering plants) – seeds are protected by a layer of tissue