BiologyLesson 1.3

The Nitrogen Cycle – process of converting nitrogen to nitrates and then back to nitrogen.

Textbook page 13

Legume plants •Important to the nitrogen cycle

•Have nitrogen-fixing bacteria that live in roots

•Convert nitrogen to nitrates that plants need to make proteins

Legume Plants• Important to the nitrogen cycle•Have nitrogen-fixing bacteria that live in roots•Convert nitrogen to nitrates that plants need to make proteins

• includes peanuts, alfalfa, clover, peas, beans

Legume Plants includes peanuts, alfalfa, clover, peas, beans

•are important to farmers

•are plowed under, decompose, and put important nitrates back into the soil

Other important facts about the nitrogen cycle:

denitrifying bacteria convert extra nitrates in the soil back to nitrogen in the air

Other important facts about the nitrogen cycle:

denitrifying bacteria convert extra nitrates in the soil back to nitrogen in the air

lightning causes nitrogen in air to become nitrates in air which rain will carry to soil

Various Lifecycles of Plants:1. Annuals –develop from a seed, make new seeds, and die in one growing season.ex. peas,grains, marigolds

Various Lifecycles of Plants:1. Annuals –develop from a seed, make new seeds, and die in one growing season. ex. peas,grains, marigolds

2. Biennials – complete lifecycle in 2 years or 2 growing seasons. 1st year they store food but don’t grow big or bloom. 2nd year they grow and produce flowers and seeds.

ex. Carrots, Geraniums

Various Lifecycles of Plants:2. Biennials – complete lifecycle in 2 years or 2 growing seasons. 1st year they store food but don’t grow big or bloom. 2nd year they grow and produce flowers and seeds.ex. Carrots, Geraniums

3. Perennials – live many years and bloom each season.

Ex. wildflowers, asparagus

Most plants belong to a group called angiosperms. Angiosperms are flowering plants with seeds and can be divided into 2 categories based on the number of cotyledons in the seed.

Monocot vs. Dicot

Cotyledon – a seed leaf in a plant embryo that containsstored food for the embryo.

monocots – one cotyledons

dicots – two cotyledons

Have fibrous roots

Have a taproot

Symmetry in biology is the balanced distribution of duplicate body parts or shapes.

There are 2 types of symmetry:

There are 2 types of symmetry:

1. Radial symmetry

Can cut the flower in half in any direction, both

halves look identical

There are 2 types of symmetry:1. Radial symmetry - Can cut the flower in half in any direction, both halves look identical

2. Bilateral symmetry-Can cut only inhalf lengthwiseand have identical halves.