KEY CONCEPT Biology is the study of all forms of life.

Earth is home to an incredible diversity of life. The biosphere includes all living things and all the places they are found. biosphere = everywhere life exists

Earth is home to an incredible diversity of life. Every part of the biosphere is connected with every other part. The biosphere includes many environments. land environments

The biosphere includes many environments. saltwater and freshwater environments Tidepool Estuary portions of the atmosphere

Biodiversity is the variety of life. Biodiversity generally increases from the poles to the equator. Biodiversity is greater in areas with consistently warm temperatures. Biodiversity is greater closer to the equator.

A species is one particular type of living thing. Members of a species can interbreed to reproduce. There are about 2 million different living species have been identified. Fig. 1.1 – Honeypot ants live in deserts where food and water are scarce. Some of the ant in the colony act as storage tanks for other ants in the colony.

All organisms share certain characteristics. Biology is the scientific study of all forms of life.

An organism is any individual living thing. All are made of one or more cells. Fig. 1.2 – Cells can work together in specialized structures, such as these leaf hairs that protect a leaf from insects. LM, magnification 700X

An organism is any individual living thing. All are made of one or more cells. All need energy for metabolism (all the chemical processes that build up or break down materials) All respond to their environment. All have DNA that they pass on to offspring. Fig. 1.3 – Reproductive strategies differ among species. The male gold-specs jawfish protects unhatched eggs by holding them in his mouth. Summarize: What characteristics are shared by all living things?

All levels of life have systems of related parts. A system is an organized group of interacting parts. A cell is a system of chemicals and processes. A body system includes organs that interact. An ecosystem includes living and nonliving things that interact.

Biologists study many different systems. Fig. 2.1 – the moray eel and the cleaner shrimp are parts of a system in which both organisms benefit. The shrimp cleans the eels mouth and gets food and protection in return. Connect: Describe how your biology class could be considered a system?

Structure and function are related in biology. Structure determines function. Proteins with different structures perform different functions. Heart muscle cells have a different structure and function than stomach muscle cells. Different species have different anatomical structures with different functions. Infer: Do you think heart muscle has the same function as arm muscle? Explain. Fig. 2.2 – The snout beetle has specialized prongs and pads on its tarsi that allow it to easily walk on both smooth and rough surfaces.

Tissues are groups of cells that perform a similar function. Multicellular organisms depend on interactions among different cell types. Tissues are groups of cells that perform a similar function. Organs are groups of tissues that perform a specific or related function. Organ systems are groups of organs that carry out similar functions. vascular tissue leaf stem lateral roots primary root SYSTEMS root system shoot system 1. CELL 2. TISSUE 3. ORGAN 3.Xylem and other tissues form roots that absorb water and nutrients. 1. Vessel elements are tube-shaped cells. 2. Vessel elements, tracheids and parenchyma cells form xylem.

Specialized cells perform specific functions. Cells develop into their mature forms through the process of cell differentiation. Cells differ because different combinations of genes are expressed. A cell’s location in an embryo helps determine how it will differentiate. Outer: skin cells help prevent Infection and dehydration. Middle: bone cells form a hard matrix that support and protect organs. Inner: intestinal epithelia have large surface area that increases absorption.

Stem cells are unique body cells. Stem cells have the ability to divide and renew themselves remain undifferentiated in form develop into a variety of specialized cell types

Stem cells are classified into three types. totipotent, or growing into any other cell type pluripotent, or growing into any cell type but a totipotent cell multipotent, or growing into cells of a closely related cell family

Stem cells come from adults and embryos. Adult stem cells can be hard to isolate and grow. The use of adult stem cells may prevent transplant rejection. The use of embryonic stem cells raises ethical issues Embryonic stem cells are pluripotent and can be grown indefinitely in culture. First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

The use of stem cells offers many currently realized and potential benefits. Stem cells are used to treat leukemia and lymphoma. Stem cells may cure disease or replace damaged organs. Stem cells may revolutionize the drug development process.

Specialized cells develop from a single zygote. Organisms are made up of specialized cells. red blood cell nerve cell Analyze: What are some of the reasons that multicellular organisms need specialized cells?

Zygotes first divide into embryonic stem cells. Stem cells develop in two stages. determination, or committing to become one cell type differentiation, or acquiring specialized structures and functions

Specialized cells perform specific tasks. Specialized cells function together in tissues, organs, organ systems, and the whole organism. Specialized cells perform specific tasks. Tissues are groups of similar cells working together. epithelial tissue connective tissue muscle tissue nervous tissue cell tissue

Organs are different tissues working together. Organ systems are two or more organs working together. Organism is all organ systems working together. ORGANS ORGAN SYSTEM ORGANISM

There are 11 major organ systems in the human body.

Homeostasis is the maintenance of constant internal conditions. Organisms must maintain homeostasis to survive in diverse environments. Homeostasis is the maintenance of constant internal conditions. Predict: What will happen to the skin in cold temperatures? Draw conclusions: Why is it so important to maintain homeostasis within the body?

Homeostasis is the maintenance of constant internal conditions. Homeostasis is usually maintained through negative feedback. Negative feedback systems return a condition to its normal (set) point. Most functions in the body are regulated by negative feed back loops Examples: Respiratory rates, thermoregulation, blood sugar levels, hunger and thirst levels, water levels

Behaviors and adaptations can help maintain homeostasis. Summarize: What is homeostasis and why is it important? Fig 2.3 – The polar bear can maintain homeostasis in very cold climates. Its hollow hair is one adaptation that helps the bear retain its body heat. SEM Magnification: 450X

Evolution explains the unity and diversity of life. Evolution is the change in living things over long periods of time. The genetic makeup of a population of a species changes. Evolution can occur through natural selection of adaptations. Adaptations are beneficial inherited traits that are passed to future generations. Fig 2.4 – Through evolution some orchids (left) have flower’s that look like insects and some insects, such as the thorn bug (right), look like parts of plants.

Evolution accounts for both the diversity and the unity of life. How? Adaptations to different environments account for diversity; similarities among all organisms (characteristics of life) suggest a common ancestor, that which unites all living things.