Plants Notes Plant Behavior Phototropism - growing towards light Geotropism - roots knowing which direction is down Thigmotropism - a plant's response to touch Ex. a vine wrapping around and climbing a tree Plant Hormones (A hormone is a messenger molecule) Auxin - controls phototropism. Causes cells in the shade to grow larger, bending a stem towards light. Gibberellin - controls plant growth, tells seeds to sprout Abscisic Acid - Stops growth (during a drought or winter) Characteristics of all plants Eukaryotes Cell wall made of cellulose Carry out photosynthesis Autotrophs 2 Stages of Photosynthesis Light Dependent Reaction requires light produces energy (ATP) takes place in the thylakoid (green disk) Light independent reaction (also called the Calvin Cycle) does not require light uses ATP from light dependent reaction to convert CO2 to glucose takes place in the stroma Factors Affecting Photosynthesis amount of water amount of light temperature
Kingdom Plantae Overview Plants divided into 2 categories 1. Nonvascular: no vascular tissue to transport water & nutrients 2. Vascular: has vascular tissue to transport water & nutrients Nonvascular Plants A rolling stone gathers no bryophytes (moss). Bryophytes: moss cannot transport water so get it by osmosis small, low to ground must be in wet area to reproduce Types of vascular tissue Xylem: carries water up from roots Phloem: carries food (sugar) down from leaves to roots Vascular plants are divided into 2 groups 1. Seedless 2. Seed Plants Ferns have spores instead of seeds Seedless Vascular Plants Ex: Ferns do NOT have seeds, use spores to reproduce have vascular tissue (roots, stems, & leaves) Seeded Vascular Plants 1. Gymnosperms: cone bearers Pines are gymnosperms Have seeds (do NOT require water to reproduce) Seeds contained in cones Ex: pine trees, spruce, & fir 2 types of cones a. seed cone is the female cone and is the large one b. pollen cone is small and is the male cone 2. Angiosperms: Flowering (includes flowers and trees that flower) seeds inside ovaries ovaries protect the seeds & eventually develop into the fruit
Angiosperms The flower is the reproductive organ 2 groups of Angiosperms 1. Monocots: One cotyledon Ex. Grass Parallel veins Flower parts in multiples of 3 Scattered vascular bundles Fibrous roots 2. Dicots: 2 cotyledon Ex. Oak tree Branched veins Flower parts in 4 s or 5 s Vascular bundles in ring Taproot
Parts of the flower sepals leaves under the petals petals: usually bright colors to attract pollinators Stamen = male part, made of anther and filament anther holds pollen filament long, thin stalk Pistil female part of flower made of stigma, style, & ovary ovary is at the base; contains ovules Style tube that pollen travels down to reach ovule Stigma top sticky part Pollination - most efficient method done by insects, wind, bats, & rodents Fertilization in Angiosperms Pollen lands on stigma & forms pollen tube down the style into the ovary & enters the ovule Ovule becomes fertilized & forms embryo & endosperm As the seed develops the ovary wall thickens & fruit develops to protect seeds Part of ovule toughens to form seed coat Plant Reproduction Plant life cycle has 2 stages known as alternation of generations. Gametophyte: haploid Sporophyte: diploid Male (pollen) and female (ovule) gametophytes join to form a zygote For example, an oak tree produces pollen. Once the pollen reaches the ovule, it becomes a gametophyte and produces gametes/sperm cells.
3 Main Plant Organs: 1. Roots 2. Stems 3. Leaves Roots Functions: Absorb water & nutrients Anchor plants in ground Store plant's food Dicots have a tap root and monocots have a fibrous root Types of roots Taproot Fibrous Parts of the Root Apical meristem: tip of root that grows in length Root hairs: increase surface area to take in more water Stems Functions: Produce leaves Transport nutrients & water Hold leaves up to sun The xylem transports water, and the phloem transports sugar
Leaves Functions of leaves Absorb light & carry out photosynthesis Gas exchange Parts of Leaf Mesophyll: contains chloroplasts Cuticle: waxy layer to keep water from evaporating Stomata: pores on underside of leaf where gases go in & out Guard cells: control opening and closing of stomata Gas Exchange Leaves take in CO2 & give off O2 Stomata allow CO2 & O2 in & out of leaf If stoma open too much then leaf loses too much Photosynthesis Equation: Water + Carbon Dioxide + Light Energy --> Glucose + Oxygen. Or in other words: 6H2O + 6CO2 + Light Energy --> C6H12O6 + 6O2. Transpiration Water evaporates from leaves As water evaporates off leaf it pulls more water up from roots