Biology For Dummies®

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small thing, this cell. "Surely they are simple," but they're actually fairly complex RNA and protein structures, that

Plants cells have a cell membrane and a cell wall, which is rigid; animal cells have only a cell membrane, which is soft.After fertilization of the eggs by sperm, the ovules within a flower become seeds, and the ovary becomes a fruit. Seeds protect the embryo, and fruits help scatter the seeds away from the parent plant.

Organisms are made of organ systems, which are made of organs, which are made of tissues, which are made of cells, which are made of molecules, which are made of atoms. Biology For Dummies, 3rd Edition, takes a look at the characteristics all living things share. It also provides an overview of the concepts and processes that are fundamental to living things. We make sure to emphasize the most important ideas in biology while taking a look at the diversity of life on planet Earth and our place in it. Different types of biologists study living things at different levels of organization, from the very tiny to the very large. Cell biologists might focus on individual cells, or even particular structures inside a cell. Physiologists study whole organisms or focus on a particular system within the body. Ecologists go big and study entire populations of organisms, or the interactions between populations and their environment. Each of these types of scientists chooses which area or system to focus on based on the questions he or she wants to answer. In the inner membranes of the mitochondria in your cells, hundreds of little cellular machines are busily working to transfer energy from food molecules to ATP. The cellular machines are called electron transport chains, and they’re made of a team of proteins that sits in the membranes transferring energy and electrons throughout the machines. Decide on your experimental treatment, what you’ll measure, and how often you’ll make measurements.

Excretory system: Maintains the balance of water and electrolytes in your body and removes wastes. Consists of your kidneys and bladder (see Chapter 16). remember Systems thinking is an approach that seeks to understand the whole system by looking at the connections between the parts of the system. Systems thinking is a very powerful approach for solving complex problems because it makes people widen their perspective and consider many different components that could contribute to the situation. By taking a wider view and considering the big picture, people are more likely to identify how they can change a system to solve a problem.

Animal cells have an organelle called a mitochondria that effectively combines oxygen and food to convert energy to a useable form. Like animals, plants are made of cells and tissues, and those tissues form organs, such as leaves and flowers, that are specialized for different functions. Two basic organ systems exist in plants: How much exercise do you get? Regular exercise uses your musculoskeletal system and strengthens your heart so it doesn’t have to pump as hard, which lowers your blood pressure. Scientists are discovering more and more about DNA; they’re also developing tools to read and alter the DNA in cells (see Chapter 9). Chances are you’re already experiencing the impacts of scientists’ work with DNA, even if you don’t know it. Why? Because scientists use recombinant DNA technology to alter organisms used in food and medicines. This technology allows them to take genes from one organism and place them into the cells of another, changing the characteristics of the receiving organism. For example, scientists alter the cells of bacteria with human genes, turning them into tiny living factories that produce human proteins needed to treat diseases. Making the Connection between Ecosystems and Evolution

What should I know before starting biology?

Digestion involves the mechanical and chemical breakdown of food molecules into their smallest subunits. Digestion begins in the mouth and continues in the stomach and small intestine. Living things grow and develop. You started life as a single cell. That cell divided to form new cells, which divided again. Now your body is made of approximately 100 trillion cells. As your body grew, your cells received signals that told them to change and become special types of cells: skin cells, heart cells, liver cells, brain cells, and so on. Your body developed along a plan, with a head at one end and a tail at the other. The DNA in your cells controlled all of these changes as your body developed. (For the scoop on the changes that occur in animal cells as they grow and develop, see Chapter 19.) In some plants, specialized reproductive structures like flowers and cones produce the egg and sperm and may create protective structures around the young embryo. Flower structure also helps with pollination, the distribution of pollen (which contains sperm) to the plant’s female parts. You’re a college student who isn’t a science major but is taking a biology class to help fulfill your degree requirements. If you want help following along in class, try reading the relevant sections in this book before you go to a lecture on a particular topic. If you need to fix a concept in your brain, read the related section after class.

The pretty parts of flowers are often showy petals, which help attract animals to flowers so they can help distribute pollen. Scientists call the ring of petals in the flower the corolla. If you’re using this book as a companion to a biology class that’s just beginning, you can follow along with the topics being discussed in class. Individuals in the population must produce more offspring than can survive.Human beings are somewhat unique among living things in that we can make conscious choices about how many offspring we have. Most other organisms, however, produce as many offspring as they can.Oxidize food molecules and transfer electrons and energy to coenzymes: Oxidation is the process that removes electrons from molecules; reduction is the process that gives electrons to molecules. During cellular respiration, enzymes remove electrons from food molecules and then transfer the electrons to the coenzymes nicotinamide adenine dinucleotide (NAD +) and flavin adenine dinucleotide (FAD). NAD + and FAD receive the electrons as part of hydrogen (H) atoms, which change them to their reduced forms, NADH and FADH 2. Next, NADH and FADH 2 donate the electrons to the process of oxidative phosphorylation, which transfers energy to ATP. Nervous system: Controls your body functions via electrical signals. Made up of your brain, spinal cord, and nerves (see Chapter 18).