Essential KNOWLEDGE for BIOLOGY Students

BIOLOGY is the study of LIFE on EARTH.

CLASSIFICATION/BIODIVERSITY

The over two million different organisms or species of living things found on Earth are classified into five Kingdoms > Plants – Animals – Fungi – Single Cells (2 types)

Animals are classified into two major groups: vertebrates (fish, amphibians, reptiles, birds, mammals) and invertebrates (insects, crustaceans, arachnids, etc.). Plants and fungi are classified into sub-groups as well.

CELLS/GENETICS

Each plant, animal, and fungi is made of many billions or even trillions of cells.

Microscopic organisms are made up of only one cell

Each cell is a very small, complex microscopic structure with a nucleus containing chromosomes made of tiny strands of DNA molecules with segments called genes.

DNA is the genetic information that determines the physical traits of a plant, animal, or fungi.

There dozens and dozens of different types of cells all with similar structures.

Green plant cells differ from animal cells because they have rigid cell walls and contain chlorophyll for the chemical production of simple sugars.

Cells divide frequently, some on a daily basis. During cell division, each cell splits into two identical copies.

Cell division enables multi-cellular organisms to develop, to grow, and to heal (repair) from injury. Specialized cell division prior to fertilization is essential to the reproduction of offspring. Cell division in unicellular organisms produces genetically identical offspring.

REPRODUCTION/SPECIE VARIATION/NATURAL SELECTION

All animals, plants, and fungi have two parents (with a few exceptions). The offspring of two parents almost always look similar but are not exact copies. Offspring all look and behave a little differently than each other. These minor variations are extremely important in the natural world where very few offspring survive to become parents. This is because some offspring are better adapted (stronger, faster, better camouflaged, etc.) to survive. Natural selection is the process that enables the “survival of the fittest” (best adapted).

BIOLOGICAL EVOLUTION

Species change over time, through natural selection. Species unable to adapt to changing conditions can eventually become extinct. Over millions of years of time, new species can be formed. The evidence for this change in species over time (biological evolution) includes the fossil record and genetic analysis

ECOLOGY/ECOSYSTEMS/ENERGY FLOW

PLANTS: Green plants get energy from the food (simple sugars) they chemically produce during photosynthesis. In ecosystems, green plants are classified as the producers.

ANIMALS: In ecosystems, animals are classified as consumers. Herbivores (like deer) get energy from eating plants, carnivores (like wolves) get energy from eating other animals, and omnivores (like bears) get energy from eating plants and animals.

FUNGI: Fungi such as mushrooms and puffballs get energy by feeding on dead plants or animals. In ecosystems fungi are the decomposers and responsible for recycling nutrients.

Predator-prey relationships, competitive relationships, and symbiotic (beneficial) relationships exist between organisms within an ecosystem. Limiting factors (resources necessary for survival) in an ecosystem control the size of populations. Competition for resources between organisms often produces increases or decreases in populations.

All ecosystems contain consumers, producers, and decomposers. The flow of food energy through ecosystems is depicted using food chains or food webs.

LIFE CYCLES

All organisms start life as a single microscopic cell. They develop and grow, and if they survive they become parents, passing their successful traits (genes/DNA) on to their offspring. Eventually they die, replaced by a new generation. Some organisms undergo metamorphosis (caterpillar> butterfly) during their life cycle.

The HUMAN BODY

The human body is made up of organ systems. Organs are made of tissues which are made of cells.

The 6 major body systems for beginners include:

Skeletal/Muscular (bones, joints, tendons, ligaments, muscles)

Nervous (brain, spinal cord, nerves)

Digestive (stomach, liver, intestines)

Cardiovascular (heart, arteries, veins)

Respiratory (lungs)