Themes of Biology categories that we use to study biology all biology questions and topics can be classified in one of the biology themes

Themes of Biology 1.Cell structure and organization 2.Reproduction 3.Metabolism 4.Homeostasis 5.Heredity 6.Evolution 7.Interdependence

Cellular Structure and Function smallest unit capable of life cells have a similar basic structure for all organisms –cells with different structures may take on different functions

Cellular Structure and Function Experiment Example A scientist observed 5 types of white blood cells each with a different structure. She wanted to know if the cells also had different functions. She knew white blood cells helped keep people healthy. To test out their functions, the scientist observed each type of cell with different types of bacteria and viruses to see if any of the cells were able to kill these organisms that could make people sick.

Reproduction process by which organisms make more of their own kind from one generation to the next

Reproduction Experiment Example A student in Wisconsin picked up some maple seeds. She wondered if the maples in Wisconsin produced a similar amount of seeds as maples by her cousin in Maine. She picked 10 trees and counted all of the fallen seeds she could find. She asked her cousin to count the seeds of 10 trees in Maine.

Metabolism process of obtaining and using energy to live What is the origin of energy for almost all life on Earth?

Metabolism

process of obtaining and using energy to live. What is the origin of energy for almost all life on Earth? – origin of energy for almost all life on Earth can be traced back to the sun

Metabolism Experiment Example A student was curious about the effect of light color on plant growth. He knew plants were able to use light energy to make their own food to grow using photosynthesis. He planted 15 seeds in 3 groups (5 plants in each group). Group A was placed under a plain white light; group B was placed under a red light; group C was placed under a green light.

Homeostasis maintenance of stable internal conditions in spite of changes in the external environment

Homeostasis Experiment Example Cacti are able to grow new roots after a rain in order to gather more water. How long could these roots grow in one day? –To test this, a student divided twenty cacti of the same species and size into two groups of ten. She watered 10 of the cacti. The other 10 cacti she did not water. After 24 hours, she measured the length of the roots of all of the cacti and compared the watered group to the non-watered group.

Heredity describes the passing on of traits from parent to offspring

Heredity Experiment Example A professor was studying bacteria. He knew when one bacteria split into two bacteria, each offspring had a copy of DNA from the parent. He wanted to know if this DNA ever changed because of mutations or if it always stayed the same. He set up an experiment where he let one bacteria reproduce for a month. He then compared the DNA of the new colonies to a sample of DNA he kept from the first cell.

Evolution “Nothing in biology makes sense except in the light of evolution” ~ Theodosius Dobzhansky Geneticist & Evolutionary Biologist

Evolution

the change of a species through time –Individual organisms do NOT evolve. –The species, instead, evolves from generation to generation. –Changes in genetic material are responsible for the changes from parent to offspring.

Evolution first proposed by Charles Darwin in 1859 only organisms with traits suited to their environment will survive and reproduce –“Survival of the Fittest”

Evolution Experiment Example Scientists knew from previous fossil finds that around 390 million years ago, the only vertebrates were fish. By 360 million years ago, four-legged animals were present on land. The team suspected that because most amphibians today live in freshwater, that a transition animal between fish and amphibians would most likely be found near freshwater. So they got out a geological map and looked for places that met their criteria: near freshwater and between 390 and 360 million years old. They settled on Ellesmere Island in Canada and began to search for fossils.

Tiktaalik roseae

Interdependence reliance on other organisms for some survival

Interdependence

reliance on other organisms for some survival All organisms also rely on the nonliving pieces of their environments for survival.

Interdependence

Ecology –study of organism relationships with each other and/or the nonliving parts of their environment

Interdependence Experiment Example A lichen is a compound organism that comes from a cyanobacteria (a bacteria that can make sugar like plants) living with a fungus. What would the survival rate be of the bacteria colonies if the fungus were to disappear? To answer this, a student applied a fungicide (a chemical that kills fungus) to lichens and counted the percentage of surviving cyanobacteria colonies.