3.2/13.3 - The Plant Kingdom

Plants are important for many reasons such as:

• life and diversity

• food

• medicinal purposes

• habitat

• clothing

• wood/building

• paper products

Plants:

• carry out photosynthesis

• have cellulose in their cell wall

• are sessile (don’t move, opposite of mobile)

• are very diverse

• are multicellular

• eukaryotic

Threats to Plants:

• deforestation

• pollution

• climate change

• invasive species

Phylogeny

- Plants are believed to have been evolved from charophytes (green algae - a protist). Evidence: - chlorophyll a and b, cell plate during cell division, cellulose in cell wall, store extra sugar as starch

Four Types of Plants

1. Non-vascular (bryophytes) - moss, needs a moist environment (no seeds)

2. early vascular (pteridophytes) - ferns (no seeds)

3. 1st seed plants - gymnosperms) - evergreen trees (seeds in cones)

4. flowering plants (angiosperms) - daisy (seeds in flowers)

Most plants live on land, some aquatic but mostly freshwater. To live on land, plants have evolved to: prevent water loss (cuticle), take in carbon dioxide (stomata), have vascular tissue (xylem and phloem)

Pollen - waterproof capsules that contain male gamete (reproductive cell, carries male genetic info), produced by anthers (produces and holds pollen) of a flower

Pollination - when male gamete in pollen enters ovule, which contains the female gamete. When they come together, they form a seed. Gametes are haploid (only one set of chromosomes) and the zygote seed they produce are diploid (contains genetic info from male and female).

• self pollination - transfer of pollen grains from 1 flower to another flower on the same plant

• cross pollination - transfer of pollen grains from 1 flower to another flower

• pollinators - bees and other insects

More than 70% of all humans food supplies are from seeds like wheat, rice and corn.

Whole grain contains the bran, endosperm and germ while ‘white’ grain only contains the endosperm.

- Bran - fiber-rish outer layer that protects the seed, contains B vitamins and trace minerals (essential nutrients)

- endosperm - middle layer that contains carbohydrates and proteins

- germ - small nutrient-rich core that contains antioxidants like vitamin E, B vitamins and healthy fats

Seed reproduction is useful because…

• it allows sexual reproduction without travelling water

• provides protection for the embryo

• it can survive many years with no water

• it can survive colder temperatures

• can be dispersed away from the parent plants

Seed functions: protect and nourish the embryo and to carry the embryo to a new location

Angiosperms:

• contain seeds in fruit (most plants)

• produce male and female gametes

• eggs protected in ovary

• cotyledons - structures that store food inside of seeds. 2 types: monocot and eudicot

Gymnosperms:

• contain seeds in cones

• most evergreen and perform photosynthesis all year

• inhabit environments that are too hot, cold or too dry for angiosperms

• soft male cones produce pollen, harder female cones produce eggs that are on the surface of the cone scales, wind carries pollen to fertilize eggs

Reproductive parts of an Angiosperm:

Male - stamen includes anther and filament

Female - pistil includes stigma, style, ovary

Monocots vs Eudicots

Fruit

• fruit is a mature ovary and contains angiosperm seeds

• development of fruits starts when an ovule is fertilized. the ovary wall develops into the fruit wall and is called the pericarp. That is the part you eat, fruit does not provide nutrients to the growing embryo but to those who eat it.

Seed Dispersal

• wind

• birds and insects

• mammals (seeds sticking on their fur)

• carried by water