Download Science Chapter 2 Webnotes

Chapter 2, Lesson 1, Reproduction
Survival depends on reproduction.
Sexual Reproduction: a new organism from 2 parents
Fertilization: male sperm joins female egg to create new life
New organism gets genetic material from both parents
Promotes variety in species….species can improve over time and be more well suited
Asexual Reproduction: a new organism from a single parent
Offspring are identical to single parent
Eliminates need of a mate
Types of Asexual Reproduction
Splitting: genetic material is copied and cell splits into 2 exact copies (bacteria)
Budding: small part of parent grows into a new complete organism (cnidarians, sponges, fungi)
Vegetative Propagation: new plant from leaf, root, or stem (runners)
Chapter 2, Lesson 2, Plant Life Cycles
Mosses and Ferns
Spores can develop into new plants without fertilization during asexual stage.
New plant creates male and female structures. Water joins the 2 and fertilization occurs and a new
plant is created.
Flowers
Flowers contain the reproductive organs of angiosperms
Petals: bright, outer part; attract pollinators
Sepals: below petals, offer protection during bud stage
Stamen: male; filament & anther; produces pollen grains that contain sperm cells
Pistil: female; stigma, style, & ovary; holds egg cells; where fertilization occurs
Complete flower: contains all parts
Incomplete flower: missing one or more parts
Perfect flower: has both stamen and pistil (lilies, gladioli, tulips)
Pollination: transfer of a yellow powder called pollen(male cells) from stamen to pistil
Can be carried by bees, birds, animals, wind. (brighter plants are usually pollinated by animals)
These cells then move down the style of pistil to ovary where fertilization occurs.
Embryo is beginning of new offspring inside a seed.
As seed grows, ovary enlarges and becomes fruit
Seed contains: embryo (material for new plant), cotyledon (food supply), seed coat (protection)
Seed moves to favorable location to germinate (become a new plant)
Self-pollination occurs when perfect flowers have both parts and make connection
Cross-pollination is when pollen from one plant pollinates a different plant
Monocot: single food supply; parallel veins, petals in groups of 3
Dicot: 2 food supplies; branched veins, petals in groups of 4 or 5
Conifer: gymnosperm; seeds but no flowers (cones)
Seeds are dispersed when cones are blown off and carried by wind.
Animals also eat seeds and then carry them to another location.
Chapter 2, Lesson 3, Animal Life Cycles
Metamorphosis: series of distinct growth stages
Complete Metamorphosis: 4 stages (butterfly)
Egg
Larva: immature stage; does not resemble adult
Pupa: hard caselike cocoon; non feeding stage
Adult
Incomplete Metamorphosis:3 stages (grasshopper)
Egg
Nymph: similar to adult but smaller and lacks wings and sex organs
Adult
External Fertilization: egg and sperm are joined outside the female’s body
Sex cells must stay moist to survive
Amphibians and most fish release sex cells into the water.
Chances of fertilization are decreased, so organisms release a large number of cells to overcome
Internal Fertilization: egg and sperm are joined inside female’s body
Increases chance of fertilization; protected from dangers outside
Some organisms develop inside eggs, others inside the mother.
Liquid inside egg is proper environment; yolk feeds the embryo
Chapter 2, Lesson 4, Traits and Heredity
Heredity: passing down of traits from parents to offspring
Inherited Trait: trait received from parents (hair/eye color, dimples, facial features)
Instinct: way of acting or behaving that an animal is born with (babies breathe, spiders spin webs)
Learned Behavior: develops over time from practice
Imprinting: social bond with another organism (ducks follow mom)
Gregor Mendel: scientist who studied genetics and found the following
Gene: contains chemical instructions for inherited traits on chromosomes inside nucleus
Genes come from both parents
Dominant Trait: stronger; masks the other
Recessive Trait: one that is hidden
Pedigree: chart used to trace history of physical traits in a family