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Biology - The Science of Biology

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    Study Guide Biology – The Science of Biology 1. Introduction to Biology Biology is the science of life. Simply put, it is the study of living things and how they work. From tiny cells to large animals and plants, biology helps us understand what makes life possible. 1.1 What Does Biology Study? Biology looks at life from many different angles: • Cells – All living things are made of cells. Biology studies how cells are structured and how they function. • Energy and metabolism – Living organisms need energy to grow, move, and survive. Biology explains how this energy is obtained and used. • Genetics and inheritance – Biology explores how traits are passed from parents to offspring through genes. • Evolution and diversity – It also examines how living organisms have changed over time and why there is such a wide variety of life on Earth. Biologists study microorganisms, plants, and animals , focusing on how their structures support their everyday activities. This helps explain how living things survive, grow, and interact with their surroundings. 1.2 Biology and Other Sciences Biology does not stand alone. It is closely connected to chemistry and physics . The chemical and physical laws that apply to non - living matter also apply to living organisms. For example, chemical reactions power life processes, and physical forces affect movement and structure. 1.3 Branches of Biology Biology is a broad subject with many specialized areas. These can be grouped into two main categories: practical biology and theoretical biology .

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    Study Guide 1.4 Practical Biology Practical biology focuses on real - world applications that directly benefit people and the environment. Examples include: • Plant breeding – improving crops for better yield and quality • Wildlife management – protecting and managing animal populations • Medical science – understanding diseases and developing treatments • Crop production – increasing food supply and farming efficiency 1.5 Theoretical Biology Theoretical biology helps us understand how living systems work. Important fields include: • Physiology – the study of how living organisms function • Biochemistry – the study of the chemical processes inside organisms • Taxonomy – the classification and naming of living things • Ecology – the study of populations and how they interact with each other and the environment • Microbiology – the study of microscopic organisms 2. Characteristics of Living Things What exactly makes something alive ? This is not an easy question to answer. Scientists still find it challenging to define “life.” However, living things share a set of key characteristics that help us recognize and understand what life is. 1. Complex Organization Living things are highly organized. They are much more complex than nonliving objects like rocks or water.

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    Study Guide • Every living thing is made of one or more cells . • Cells are the basic units of life and are usually too small to see without a microscope. • Similar cells work together to form tissues . • Tissues combine to make organs , such as the stomach or kidneys. • Organs that work together form an organ system . • All organ systems together make up an organism . This clear, layered organization is a key feature of all living things. 2. Metabolism All living things carry out metabolism , which refers to the chemical reactions that keep them alive. • Metabolism involves taking in materials from the environment. • These materials are changed inside cells to build structures and release or use energy . • Energy is needed for growth, movement, repair, and other life processes. Nonliving things do not have metabolism — they do not carry out chemical reactions to sustain themselves. 3. Responsiveness Living things can respond to stimuli , which are changes in their environment. Examples of stimuli include: • Light • Heat • Sound • Chemicals • Touch or pressure To detect these changes, organisms have special structures such as eyes, ears, and taste buds .

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    Study Guide Coordination and Response • The body uses nerves and hormones to coordinate responses. • Effectors , such as muscles and glands, carry out the response. • Energy is usually required for these actions. Living organisms also show behavior , meaning they actively change how they act in response to the environment. For example, an animal may move toward food or away from danger. This active response is different from nonliving objects, like a rock rolling downhill, which move passively. 4. Growth Living things grow in a very specific way. • Growth happens when an organism takes in materials from its environment. • These materials are reorganized to form new parts of the organism. • Energy from metabolism is used to support this process. A key feature of growth is that living organisms turn unlike materials into more of themselves . For example, when a person eats food, the body breaks it down and uses it to build new cells. Nonliving things cannot do this. 5. Reproduction Living things can reproduce , meaning they can make copies of themselves while still alive. Types of Reproduction • Asexual reproduction ○ Involves only one parent. ○ The offspring are usually identical to the parent. ○ Example: Bacteria reproduce by binary fission , where one cell splits into two. • Sexual reproduction

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