Study for Monday - Biology Notes PDF

# Study for Monday ## Unit one - Chemistry & The Cell / Organic Compounds - All living things must maintain **homeostasis** in order to stay alive - **Homeostasis**: A balanced state in an organism's body. - Failure to maintain homeostasis results in disease or death. - **Feedback Mecha...

# Study for Monday ## Unit one - Chemistry & The Cell / Organic Compounds - All living things must maintain **homeostasis** in order to stay alive - **Homeostasis**: A balanced state in an organism's body. - Failure to maintain homeostasis results in disease or death. - **Feedback Mechanisms** are often used to maintain homeostasis - Feedback mechanisms are cycles in which the product of one reaction causes another to start or stop. - While organisms are balanced, they are not unchanging. The term used to describe the balanced state is **dynamic equilibrium**. - Dynamic equilibrium: A balanced state created by many small, opposing changes. ## Life Processes - All living things carry out the same basic chemical processes. Taken together, these processes make up an organism's **metabolism**. - **Metabolism**: All the chemical processes that take place in an organism. - **Nutrition**: Use nutrients for growth, synthesis, repair and energy. - **Cellular Respiration**: Convert energy in food into a usable form (ATP). - **Synthesis**: Make complex compounds from simple substances. - **Transport**: Absorb and distribute materials throughout the body or the cell. - **Regulation**: Control and coordination of life processes. - **Excretion**: Remove wastes produced by metabolic activities. - **Reproduction**: Pass on genes to offspring. ## Inorganic Molecules: Simple Compounds - **Water (H₂O):** Most common substance in all living things (about 60% of body mass) - Needed for chemical reactions (which won’t happen in “dry” conditions) - Dissolves molecules into solution, allowing them to be **transported** through the body. - **Carbon Dioxide (CO₂):** - With water, used by plants to make glucose during **photosynthesis**. - Waste product of **cellular respiration** (aerobic). - **Oxygen (O₂):** Needed by most (not all) organisms for **cellular respiration**. - Released by plants and algae as a waste product of **photosynthesis**. - **Cellular Respiration (aerobic)**: Process that uses oxygen to release energy from glucose (sugar). Used by most organisms. - **Fermentation (anaerobic)**: Process that releases energy from glucose without using oxygen. Provides less energy, so only used by a few simple organisms such as some bacteria and yeast. These organisms do not need to take in oxygen. - **Nitrogen (N₂):** - Most common gas in air (70%). - Needed to make protein and nucleic acids. ## Example of a Controlled Experiment: - **Hypothesis**: - If people chew gum, it will improve their memory. - **Independent variable**: - Chewing gum - Some people will chew gum, some will not. - **Dependent variable**: - Memory - All groups should have their memory checked both before and after the experiment to see if it was improved. - **Control Group**: - Doesn’t chew gum (remember - the control group never receives the new treatment) - **Experimental Group (Independent Variable)**: - Group that chews gum. - **Constants**: - Should be the same for both groups: - People in each group should be of similar health with similar memory, with similar mixes of sexes, ages, and ethnicities. Each group should also be tested in the same way. - **Data Collected**: - You should test people's memories both before and after the experiment. ## Characteristics of a good experiment: - Can be repeated the same way and get the same results. - Have large sample size/many test subjects. - Are performed over longer periods of time. - Test only one independent variable. All other characteristics of the tested groups should be the same. - Are peer reviewed - examined by other scientists to determine its accuracy. - Must test the hypothesis and show whether it is wrong or right. - Is objective - the experiment and conclusion are fair and unbiased. Fact and opinion are not mixed. - The experiment follows established ethical and legal standards. ## The Cell - The **cell** is the basic unit of structure and function in all living things. - **Cell Theory** has three parts: - All living things are made of one or more cells. - **Unicellular** - single celled organisms (amoeba, paramecium) - **Multicellular** - have more than one cell; may be just a few cells, or many trillions of cells. - Almost all structures in multicelled organisms are either made of or by cells. - Cells carry out all life processes. - Everything you do is the result of the work of your cells - walking, talking, even thinking and feeling. When you get sick, it is because your cells are not working correctly. - All cells come from preexisting cells. - This seems obvious now, but at one time people believed in **spontaneous generation**, the idea that living things regularly emerged from nonliving things. - **Exceptions to the Cell Theory** - **Viruses** are not made of cells. Viruses do not carry out all life processes, so many biologists do not consider them true living things. - The first cell could not come from another cell. (BIG QUESTION? How did first cell begin?) ## Organization - From smallest to largest - **Molecules** - **Organelles** - Cell structures - **Cells** - **Tissues** - Group of cells with the same structure and function. - **Organs** - Made of different tissues working together for the same function. - **Systems** - Groups of organs that work together for the same function. - **Organism** - living thing (species) - **Population** - members of the same species living in the same place at the same time. - **Community** - Many different populations living in the same place at the same time. ## Cell Organelles - These are the tiny cell parts that make up a cell. - **Nucleus:** - Controls the cell - Contains **hereditary material** (chromosomes, genes, DNA) - **Cytoplasm:** (technically not an organelle) - Fluid/liquid in the cell - mostly water - Helps **transport material** - **Mitochondrion:** - Carries out **cellular respiration** - Gives cell usable energy in the form of **ATP** (powerhouse of the cell) - **Ribosome:** - Makes proteins by joining amino acids (**protein synthesis**) - **Vacuole:** - Stores food, water and waste - Food vacuoles with lysosomes may digest large molecules. - Waste vacuoles may excrete waste out the cell membrane - Plant cells have LARGE water vacuoles. - **Chloroplast:** - Contains **chlorophyll** and carries out **photosynthesis**. - Found ONLY in plant cells and algae cells. - **Cell Wall:** - Gives shape, structure and protection. - NEVER found in animal cells. - **Cell Membrane:** - Separates cell interior from outer environment. - Made of two layers of lipids plus proteins embedded in the lipid layers. - Controls what enters and leaves the cell using **membrane proteins**. This is part of **regulation** and **homeostasis**. - Has **receptor molecules** (proteins) that pick up signals from other cells. - Also has protein “tags” that identify the cell (see **immune system**). - **Diffusion**: movement of substances from an area of high concentration to an area of low concentration. A form of **passive transport** that does NOT require energy. - **Osmosis**: diffusion of water. Water moves into or out of the cell from an area of high concentration to an area of low concentration. - **Active Transport**: substances move into or out of cells from an area of low concentration to an area of high concentration. Requires the use of energy (ATP). ## Photosynthesis and Cellular Respiration - Photosynthesis and Cellular Respiration are opposite reactions! They are important in cycling oxygen, carbon, hydrogen and water through the environment. **COMMON MISTAKES!** - "Plants do photosynthesis, animals do cellular respiration." - All organisms, including plants, use **cellular respiration** to get their energy as ATP. - "Respiration is breathing." - Breathing is not respiration. Breathing exchanges the gases needed for respiration. Inhaling oxygen and exhaling carbon dioxide does not give you ATP. - "Oxygen is used to breathe." - This is backwards. Breathing is used to get oxygen which is used for cellular respiration. Without oxygen, you have no respiration, no ATP, and no energy. - "All living things need oxygen. All living things need to breathe." - Anaerobic organisms (such as yeast and some bacteria) do not need oxygen, and do not breathe. ## Nutrition and Energy - All life processes are chemical activities which make up your **metabolism**. - **Nutrition**: Taking in nutrients (food) for various activities including: - growth - repair damaged tissue - synthesis (building) - cellular respiration (energy) - **Ingestion**: To take nutrients into the body. - **Digestion**: To break down nutrients (polymers) into smaller molecules (monomers). - Nutrients must be broken down into smaller parts so that they can be absorbed into the blood and cells of organisms. - Carbohydrates (such as starches) are digested into monomers called simple sugars. - Lipids (such as fats and oils) are digested into monomers called fatty acids. - Proteins (such as meat and fish) are digested into monomers called amino acids. - **Autotrophic Nutrition**: Organisms take inorganic molecules (CO₂ & H₂O) and convert them into organic nutrients (carbohydrates such as sugars and starches). - **Autotroph** = makes its own food. - **Photosynthesis** is most common form of autotrophic nutrition. - **Producers** such as plants, algae and some bacteria (cyanobacteria) are common autotrophs. - **Heterotrophic Nutrition**: Organisms must consume nutrients from other organisms. - **Heterotroph** = can’t make its own food. - All animals and all fungi and some bacteria are heterotrophs. - **Carnivores**: eats animals - **Herbivores**: eats plants or algae - **Omnivores**: eats both plants and animals - **Decomposers**: breaks down dead matter and waste - Decomposers are important decay organisms for recycling nutrients. - **Photosynthesis**: Process in which sun's energy is stored in the chemical bonds of sugar. - Requires sunlight, water H₂O and carbon dioxide CO₂. - Makes glucose C₆H₁₂O₆ as food. - Water H₂O and oxygen O₂ are waste products. ## Lab Skills: - **Observation**: What is seen or measured. - **Inference**: A conclusion based on observation or evidence. - **Hypothesis**: A prediction based on available evidence. A good hypothesis states both cause and effect. - A correct hypothesis can be tested and falsified (proven incorrect) using an experiment. - The easiest way to write a correct hypothesis is as an "if-then" statement. (Ex: If I give patients this pill, then they will not get sick.) - **Theory**: An explanation of natural events that is supported by strong evidence. - Theories tie together many scientific facts, hypotheses and laws. - **Common Mistake:** “Theories are things that are opinions, or are not proven.” - This is an incorrect use of the word "theory" in a scientific context. A scientific theory is not a simple guess or conjecture, and is strongly supported by evidence. ## Controlled Experiments - Compares the results of an experiment between one or more experimental groups with a "normal" group. - **Experimental group**: Group being tested or receiving a special treatment. - **Control group**: "Normal" group. Should be identical to experimental group in every way except one: it does not receive the new treatment. - **Placebo**: A sugar pill or other "fake" treatment given to the control group. Usually only needed when using human subjects.