Plant Life Cycles Ch 6 section 1 and 2

What Are the Functions of Roots, Stems, and Leaves?  Roots -3 Main functions -anchor the plant in the ground -absorbs water and minerals from the soils -sometimes stores food

Types of Roots  - Fibrous  - consists of many similarly sized roots that form a dense tangled mass.  - remove lots of soil when pulled out of the ground  - examples- grass, corn, onions  -Tap - one long, thick main root - smaller, roots branch off the main root - hard to pull out of the ground - examples- carrots, dandelions, cactus

Root Structure  Root cap- rounded and covers the tip of the root  Root hairs- grow out of the roots surface  Absorb water and minerals  Help anchor plant in soil  Tissues  Xylem- water and nutrients move through this  Phloem- transfers food

Root Structure. Plant Structures

Stems  Two Main functions  - carries substances between the plant’s roots and leaves  - provides support for the plant and holds up the leaves

Structure of the Stem  -can be either woody (hard and rigid) or herbaceous (contain no wood and are often soft). Both contain phloem and xylem tissues  Woody Stems  Outer layer is bark (protective)  Cambium – creates new phloem and xylem  Annual rings  Represents a tree’s yearly growth  Made of xylem  Xylem that forms in the spring are large and have thin walls because of rapid growth. Produce a wide, light brown ring  Xylem that forms in the summer grows slowly, are small and have thick walls. Produce a thin, DARK ring  One pair of light and dark rings represents a years growth  In wet years the tree’s annual rings are wide. In dry years, the rings are narrow

Leaves  Capture the sun’s energy and carry out the food making process of photosynthesis.  Structure of a Leaf  Surface layer  Stomata- small openings that control the gasses entering and exiting the leaf.  Inside the leaf  Veins containing xylem and phloem  The Leaf and Photosynthesis  Cells containing the most chloroplasts are found near the upper surface  Carbon dioxide enters through the stomata  Water travels from the roots through the xylem tissue  Controlling Water Loss  Transpiration- water evaporating from plant’s leaves  Prevented by closing the stomata

Leaf Structure Each structure helps a leaf produce food. Plant Structures

Stomata Stomata can slow water loss. Plant Structures

How Do Seeds Become New Plants  Seed Structure  3 main parts  Embryo  Young plant that develops from a fertilized egg  Has the roots, stems, and leaves of new plant  Cotyledons (seed coats)  Food is either stored here or outside the embryo  Seed coat  Outer covering that protects the seed and food from drying out  Allows the seed to remain inactive for long periods of time  In many plants the seeds are surrounded by a fruit

Seed Dispersal  Scattering of seeds  Methods  Animals eat the fruit, the seeds pass through digestive system and are deposited in new areas  Attach to articles of clothing or fur with hook like structures and fall off in a new area  Water and wind dispersal  Seeds that are dispersed far away from parent plant has a better chance for survival because there’s no competition

Germination  Occurs when the embryo begins to grow again and pushes out of the seed  Begins when the seeds absorbs water.  Roots grow downward first and then stem and leaves grow upward.

What Are the Structures of a Flower?  Main Function of a flower is reproduction  -A typical flower contains  Sepals  Petals  Stamens  Pistils  The color, shape and scent of a flower attracts insects and other animals that ensure that pollination occurs.  Pollination is transfer of pollen from male structures to female structures

Sepals and petals  Sepals enclose the bud and protect the developing flower- often green in color  Petals are found under the sepals and are generally the most colorful part of the flower

Stamens  Male reproductive part  Filament- thin stalk  Anther- contains the pollen- found at the top of the filament

-Pistils  Female reproductive part  Stigma- sticky tip- catches the pollen  Style- tube connecting the stigma to the ovary- pollen travels down it  Ovary- hollow base that contains the eggs, protects the seeds as they develop

Ch 6 Lesson 2

What are the Stages of a Plant’s Life Cycle?  Two Different Stages  Sporophyte  First stage where plant produces spores or seeds (tiny cells) that can grow into new organisms  Gametophyte  Second stage that produces the sex cells; sperm or egg.

Plant Reproduction Plant Life Cycle All plants go through two stages in their life cycle. Which are the sporophyte and gametophyte stages?

 Angiosperms are classified based on the length of their life cycle  Annuals  Flowering plants that complete their life cycle within one growing season  Examples- marigolds, petunias, wheat, cucumbers  Biennials  Complete their life cycle in 2 years.  First year- germinate and grow roots, very short stems and leaves  Second year- grow larger and produce flowers and seeds  Examples- parsley, celery, and foxglove flowers  Perennials  Flowering plants that live for more than 2 years  Flower every year

How Do Plants reproduce?  All plants undergo sexual reproduction that involves fertilization.  Fertilization occurs when the sperm enters the egg. The fertilized egg is called a zygote

Asexual Reproduction  Doesn’t involve flowers, pollination, or seeds  Can happen quickly  Can reproduce unfavorable traits since there’s no new genetic information being passed to offspring

Non Vascular and Seedless Plants  Release spores, instead of seeds, that grow into gametophytes.  When the gametophytes produce the egg and sperm there must be water available for the sperm to swim to the egg.  Examples- mosses, liverworts, hornworts, ferns, and horsetails.

Gymnosperms  Have reproductive structures called cones  Reproduction Steps Cone Production  Covered in scales  Two types- male and female  Pollen Production and Ovule Development  Male cones produce pollen  Female cones produce ovules that contain an egg. Female cones contain at least one ovule at the base of each scale. The ovule later turns into a seed  Pollination  Transfer of pollen to egg is done by wind.  Fertilization  Ovule closes and seals in the pollen.  Scales close and zygote develops  Seed Development  Female cones remain on the tree while seeds mature  Cone grows in size, sometimes taking up to 2 years to mature  When mature, the scales open and release the seed into the air

Angiosperms  Pollination  Flower is pollinated when pollen lands on the stigma  Pollen travels down the style to the ovary.  Zygote develops within the seed’s embryo  Fruit Development and Seed Dispersal  As the seeds develops the ovary changes into fruit, which encloses the seeds.