Biology Basics

• The biological hierarchy of organisation starts at the simplest level to the most complex.
• These are the atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem and biosphere.
• The biosphere is the largest and most complex, it includes all environments inhabited by life.
• The atom, molecule and macromolecule are chemistry.
• Cytology or cell biology includes organelle and cells.
• There are many related studies to cytology, these include, microbiology (the study of microscopic organisms) and molecular genetics (the study of genetic material).
• Tissues are the study of histology.
• Anatomy and physiology include the next three levels, organ, organ system and organism.
• Population is covered by population genetics, paleontology and evolutionary biology.
• Population genetics is the study of the inheritance between generations of organisms.
• Evolutionary biology is the study of populations and species throughout time.
• Paleontology studies extinct species.
• The community, ecosystem and biosphere are covered in the study of ecology.
• There are many other studies in biology.
• All matter is made from chemical elements.
• An atom is the smallest piece of an element.
• Atoms come together to form molecules.
• Some molecules are small, but molecules such as fat, DNA, starch and proteins are large. These are referred to as macromolecules.
• Atoms, molecules and macromolecules are the building materials that living organisms need to remain alive, they provide the nutrients needed.
• When macromolecules come together they can form organelles.
• Organelles perform tasks inside the cells.
• Cells are the first level considered to be alive, they contain a combination of organelles necessary to support life.
• Cells form tissues which have a common function.
• Organs are formed from tissues that unite and perform at least one function, eg. Lungs, heart and liver.
• Many organs together form organ systems, they all have an overall function, eg the digestive system, the circulatory system and the skeletal system.
• The levels higher than individual organisms are population, community and ecosystem.
• Populations are a group of organisms who belong to the same species.
• Community’s are different species who live in the same area.
• Ecosystems are the interactions between the community and all the non living aspects, e.g. water and sunlight.

Basic Biological Principles

• The cell is the lowest level that can perform all activities necessary for life and reproduction.
• All organisims are made of cells.
• Singled celled organisms are called unicellular.
• Organisms made up of multiple cells are called multicellular.
• Both unicellular and multicellular have the ability for the cells to divide and form new cells.
• All cells use DNA as the chemical material of genes.
• All cells are either prokaryotic or eukaryotic.
• Prokaryotic means “before the nucleus.” They lack the internal membranes and are unicellular.
• Bateria are prokaryotic.
• Eukaryotic cells have a nucleus, which encloses the DNA.
• Form fits functions – All organisms have certain structures to allow them to perform their tasks. The shape and organisation of a part reflects what it does and the job the part has will reflect the structure of the part.
• Living organisms have many mechanisms to maintain a constant internal environment, which keeps the organism alive, this is called homeostasis.
• Homeostasis is a negative feedback system to keep balance so the organism remains in optimal health
• Only reproduction allows species to pass on their genes.
• Inheritance is the total amount of genetic characters passed from parent to offspring.
• Genes are made form DNA, which stores information.
• Every cell in your body has a copy of all the DNA inherited from your parents.
• Cells make copies of DNA before they divide and pass this information on to the cells it produces.
• In reproduction the DNA is passed on to the offspring by the egg cell combining with the sperm cell which results in a fertilized cell containg both parents DNA.

Interaction with the Environment

• All organisms interact with the environment, living and nonliving components.
• E.g. a tree
o The roots absorb water and minerals from the soil.
o Leaves absorb carbon dioxide.
o The tree releases oxygen into the air.
o It’s roots break up rocks which help form soil.

Life Requires Energy
• Energy is the ability to do work. All living organisms use it.
• Energy is used by cells to allow them to perform all their tasks.
• The chemical ractions that happen in the cells are called its metabolism.
• Photosynthesis is cells that have the ability to harness the power of the sun and convert it into chemical energy in sugars.
• The cells that can’t perform photosynthesis get their energy from the photosynthetic cells.
• Photosynthetic organisms are called producers. The energy procucers make flows to the consumers (animals).
• The animals either eat the plants directly or indirectly, by eating other animals who have eaten the plants.
• To save on energy many molecules are reused by breaking them down into atoms and rebuilding them into other molecules over an over.

Adaptation and Evolution

• Camouflage is an example of evolutionary adaptation.
• Adaptation is a trait that’s inherited to help with the survival and reproduction of an organism.
• The combinations of a species inherited genes vary, individuals with the more helpful variations may live longer and produce more offspring. This is called natural selection.
• Evolution means “a process of change.”

Unity and Diversity

• Biologists have names and identified about 1.8 million species.
o 290,000 types of plants
o 52,000 kinds of vertebrates (animals with backbones)
o 1,000,000 kinds of insects
• There is unity under all the diversity. DNA is universal and natural selection is another.

Grouping Life

• Similar species are grouped together.
• There are three domains, Bacteria, Archaea and Eukarya.
• Domain Bacteria and domain Archaea are two very different organisms which have prokaryotic cells.
• Domain Eukarya are organisms with eukaryotic cells.
• Domain Eukarya are grouped into four kingdoms,
o Kingdom Protista
o Plantae
o Fungi
o Animalia