Characteristics of Living Things (Lesson 1.3)

Living things respond to their environment.

A stimulus is a signal to which an organism responds. For example, some plants can produce unsavory chemicals to ward off caterpillars that feed on their leaves.

How do different fields of biology differ in their approach to studying life?

Biology includes many overlapping fields that use different tools to study life from the level of molecules to the entire planet.

Living things grow and develop.

During development, a single fertilized egg divides again and again. As these cells divide, they differentiate, which means they begin to look different from one another and to perform different functions.

Living things reproduce, which means that they produce new similar organisms.

Most plants and animals engage in sexual reproduction, in which cells from two parents unite to form the first cell of a new organism.

Biology is the study of life. But what is life?

No single characteristic is enough to describe a living thing. Also, some nonliving things share one or more traits with organisms. Some things, such as viruses, exist at the border between organisms and nonliving things.

Metabolism

The combination of chemical reactions through which an organism builds up or breaks down materials

Lab Safety

The single most important safety rule is to always follow your teacher's instructions. Wearing appropriate protective gear is also important while working in a laboratory. Remember that you are responsible for your own safety and that of your teacher and classmates. If you are handling live animals, you are responsible for their safety too.

Over generations, groups of organisms evolve, or change over time.

___________ change links all forms of life to a common origin more than 3.5 billion years ago. ____________ of this shared history is found in all aspects of living and fossil organisms, from physical features to structures of proteins to sequences of information in DNA. _____________ theory is the central organizing principle of all biological and biomedical sciences.

Living things are based on a universal genetic code

All organisms store the complex information they need to live, grow, and reproduce in a __________ _________ written in a molecule called DNA. That information is copied and passed from parent to offspring and is almost identical in every organism on Earth. The information coded in your DNA is similar to organisms that lived 3.5 billion years ago.

Living things are made up of one or more cells—the smallest units considered fully alive.

Cells can grow, respond to their surroundings, and reproduce. Despite their small size, cells are complex and highly organized. For example, a single branch of a tree contains millions of cells.

Living things obtain and use material and energy to grow, develop, and reproduce.

For example, leaves obtain energy from the sun and gases from the air. These materials then take part in various metabolic reactions within the leaves.

What characteristics do all living things share?

Living things are made up of basic units called cells, are based on a universal genetic code, obtain and use materials and energy, grow and develop, reproduce, respond to their environment, maintain a stable internal environment, and change over time.

Homeostasis

Living things maintain a relatively stable internal environment, even when external conditions change dramatically. All living organisms expend energy to keep conditions inside their cells within certain limits. For most organisms, any breakdown of homeostasis may have serious or even fatal consequences.

Matter

Life requires __________ that serves as nutrients to build body structures, and energy that fuels life's processes. Some organisms, such as plants, obtain energy from sunlight and take up nutrients from air, water, and soil. Other organisms, including most animals, eat plants or other animals to obtain both nutrients and energy. The need for matter and energy link all living things on Earth in a web of interdependent relationships.

Living things are made of cells.

Many living things consist of only a single cell and are called unicellular organisms. Plants and animals are multicellular. Cells in multicellular organisms display many different sizes, shapes, and functions.

All living things reproduce.

Newly produced individuals grow and develop as they mature. During growth and development, generalized cells typically become more different and specialized for particular functions. Specialized cells build tissues, such as brains, muscles, and digestive organs, that serve various functions.

What are the central themes of biology?

The study of ____________ revolves around several interlocking big ideas: The cellular basis of life; information and heredity; matter and energy; growth, development, and reproduction; homeostasis; evolution; structure and function; unity and diversity of life; interdependence in nature; and science as a way of knowing.

What is the job of science?

Using observations, questions, and experiments to explain the natural world in terms of natural forces and events. Successful scientific research reveals rules and patterns that can explain and predict at least some events in nature.

Asexual reproduction

in which a single organism produces offspring identical to itself.