A Walk Through 7th Grade Science

Interactions of Living Things

Abiotic vs. Biotic

ABIOTICNonliving factor.

Light, water, heat, rocks, energy,

minerals.

BIOTICLiving factor.

Animals, plants,

bacteria.

• Dichotomous Key: – An aid that is used to identify organisms based on

the answers to a series of questions.

Interactions of Living Things

Interactions of Living Things

• Ecosystem: A community of living organisms and their interrelated physical and chemical environment.

Interactions of Living Things

• Biological Diversity: The variety and complexity of species present and interacting in an ecosystem and the relative abundance of each.

• BIOLOGICAL DIVERSITY IS A GOOD THING!

Interactions of Living Things

• Niche: The role played by an organism in an ecosystem; its food preferences, requirements for shelter, special behaviors and interactions with other organisms in its habitat.

Interactions of Living Things

• Trophic Levels

What happens to the amount of energy?

•Producer•Herbivore•Carnivore•Consumer•Omnivore

Interactions of Living Things

Interactions of Living Things

• Equilibrium: The ability of an ecosystem to maintain stability among its biological resources.

• Homeostasis: The tendency for a system to remain in a state of equilibrium by resisting change.

Plants

• Photosynthesis: Process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make food.

Plants• Chlorophyll: A green pigment that captures

light energy for photosynthesis.This is what makes plants green!

• Stomata: Opening in a leaf that allows gas exchange.

• Transpiration: The process by which plants release water vapor into the air.

Cycles• Carbon Cycle

Cycles• Water Cycle

Cycles• Succession: The series of changes that occur

in an ecosystem with the passing of time.

Cells

• Cell: The smallest unit that can perform all life processes.

• Cell Cycle: The life cycle of a cell.

Cells

• Cell Theory1. All living things are composed of cells2. Cells are the basic function and structure of life3. All cells come from other cells

Cells

• Prokaryotic vs. Eukaryotic

No Nucleus!

Cells

• Cell Processes– Diffusion – movement of particles from region of high

density to low density– Osmosis – movement of water through a membrane– Active Transport – moving substances across cell

membrane (requires ENERGY from cell)– Passive Transport – moving substances across cell

membrane (no energy required)– Enzymes – protein that speeds up a chemical reaction

Mitosis and Meiosis

Cells

• In case you thought cells were boring…http://www.youtube.com/watch?v=-zafJKbMPA8

• What are the two different types of cells?– Plant and Animal

• What are the components of cells called?– Organelles

• Which organelle controls the cell?– Nucleus

Levels of Organization

Types of Reproduction

Guess the Type of ReproductionVegetative ReproductionFission

CloningMitotic Cell Division

BuddingRegeneration

Structure = Function

Heredity

• Dominant Trait - CAPITAL LETTERS• Recessive Trait – lower case letters• Co-Dominance – mixture of both• Example:– In purple people eaters, one-horn is dominant and

no horns is recessive.• One-horn: H• No horns: h

Heredity

• Homozygous: Same allele• Heterozygous: Different alleles

• Example:– In purple people eaters, one-horn is dominant and

no horns is recessive.• Homozygous: HH or hh• Heterozygous: Hh

1. How creepy is this?2. What are the two possible

genotypes for this people eater (he has one horn).

Heredity – Brain Pop!

Quiz Yourself!

Quiz Yourself!

Quiz Yourself!

Quiz Yourself!

Practice a Punnett Square

One flower is heterozygous red (Rr) and it is crossed with a homozygous white (rr) plant. Use a Punnett square to determine the probability of one of their offspring having a red color. R r

r

r

Rr

Rr

rr

rr

50% Rr Red50% rr White

Genotype vs. Phenotype

Genetics - Pedigrees

Genetics

• Mutation – a change in a gene.

Evolution

• Adaptation: A characteristic that improves an individual’s ability to survive and reproduce in a particular environment.

Evolution

• Evolution: The process in which inherited characteristics within a population change over generations such that new species sometimes arise.

Natural Selection

• The process by which individuals that are better adapted to their environment survive and reproduce more successfully than less adapted individuals do.