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Biology CH2
Chapter 2 Study Questions
| Question | Answer |
|---|---|
| What is matter? | Anything that takes up space and has mass. |
| What is an atom? | The smallest unit of an element that cannot be broken down by ordinary means |
| What are the four major bulk elements in living organisms? | Carbon, Hydrogen, Oxygen, and Nitrogen (CHON). |
| Why is nitrogen important biologically? | It is a component of all amino acids and proteins |
| What mineral elements are required in large amounts? | Phosphorus, Sodium, Magnesium, Potassium, and Calcium. |
| What are two major functions of calcium? | Bone structure and muscle contraction. |
| What are trace elements? | Elements required in very small amounts. |
| Name five trace elements. | Boron, Fluorine, Iron, Zinc, and Copper. |
| What is iron's role in the body? | It is the central atom in hemoglobin and helps transport oxygen. |
| Why can iron, zinc, and copper be dangerous? | hey become toxic in excessive amounts. |
| What are the three main subatomic particles? | Protons, Neutrons, and Electrons. |
| What charge does a proton have? | Positive (+) |
| Where are protons located? | In the nucleus. |
| What charge does a neutron have? | No charge (neutral). |
| Where are neutrons located? | In the nucleus. |
| What charge does an electron have? | Negative (-). |
| Where are electrons located? | In electron shells around the nucleus. |
| What is an atomic symbol? | C = Carbon |
| What is atomic number? | The number of protons in an atom. |
| What identifies an element? | Its atomic number |
| What is atomic mass? | The combined number of protons and neutrons. |
| Which side of the periodic table contains the most electronegative elements? | The right side. |
| Why are noble gases inert? | Their valence shells are completely full. |
| What is an ion? | An atom with a net charge caused by gaining or losing electrons. |
| What happens when an atom loses an electron? | It becomes positively charged. |
| What happens when an atom gains an electron? | It becomes negatively charged. |
| What is an isotope? | Atoms of the same element with different numbers of neutrons. |
| What stays the same in isotopes? | The number of protons (atomic number). |
| How many protons and neutrons does Carbon-12 have? | 6 protons and 6 neutrons |
| How many protons and neutrons does Carbon-13 have? | 6 protons and 7 neutrons |
| How many protons and neutrons does Carbon-14 have? | 6 protons and 8 neutrons |
| What radioactive isotope is used for radiometric dating? | Carbon-14 |
| Why can't Carbon-14 date dinosaur fossils? | The fossils are too old and all C-14 has decayed |
| What is the approximate half-life of Carbon-14? | Nearly 6,000 years |
| What is Cobalt-60 used for? | Sterilizing surgical equipment |
| What isotope is commonly used in PET scans? | Fluorine-18 |
| What can PET scans help detect? | Tumors such as thyroid cancer |
| How can radioactive isotopes be used in medicine? | Targeted radiation therapy to shrink tumors |
| What is an electron shell? | A region around the nucleus where electrons are found |
| How many electrons can the first shell hold? | 2 electrons. |
| How many electrons can later shells hold (simplified biology model)? | 8 electrons |
| What is a valence shell? | The outermost electron shell. |
| Why is the valence shell important? | It determines bonding behavior. |
| How many electrons does hydrogen have? | 1 electron. |
| What is hydrogen's atomic number? | 1 |
| What is carbon's atomic number? | 6 |
| How many valence electrons does carbon have? | 4 |
| How many bonds can carbon form? | 4 covalent bonds |
| Why is carbon important in biology? | It forms the skeleton of organic molecules |
| What is nitrogen's atomic number? | 7 |
| How many valence electrons does nitrogen have? | 5 |
| What is oxygen's atomic number? | 8 |
| How many valence electrons does oxygen have? | 6 |
| How many bonds does oxygen usually form? | 2 bonds |
| What is a molecule? | Two or more atoms chemically bonded together. |
| What is a compound? | A molecule made from different types of atoms. |
| Give three examples of compounds. | Water (H₂O), DNA, and proteins |
| What does CH₄ represent? | Methane (1 carbon and 4 hydrogens) |
| What is an ionic bond? | A bond formed by electron transfer between atoms |
| How are ions held together in an ionic bond? | By attraction between opposite charges. |
| What is a common example of an ionic compound? | Sodium chloride (NaCl) |
| What happens to sodium in NaCl formation? | It loses one electron and becomes positive |
| What happens to chlorine in NaCl formation? | It gains one electron and becomes negative |
| Are ionic bonds strong in water? | No, they dissolve easily in water. |
| What is a covalent bond? | A bond formed by sharing electrons |
| Are covalent bonds stronger than ionic bonds? | Generally yes |
| What is a nonpolar covalent bond? | Equal sharing of electrons |
| Give examples of nonpolar covalent molecules. | H₂, O₂, and N₂ |
| What is a polar covalent bond? | Unequal sharing of electrons |
| Why is water polar? | Oxygen attracts electrons more strongly than hydrogen |
| Which part of water is slightly negative? | The oxygen end |
| Which part of water is slightly positive? | The hydrogen ends |
| What is a hydrogen bond? | A weak attraction between polar molecules. |
| Between what molecules do hydrogen bonds commonly form? | Water molecules |
| Why are hydrogen bonds important? | They stabilize DNA, proteins, sugars, and many biological structures |
| Approximately what percentage of Earth's surface is covered by water? | About 75% |
| Approximately what percentage of body weight is water? | About 60% |
| What is cohesion? | Attraction between water molecules |
| What property results from cohesion? | High surface tension |
| What insect can walk on water due to surface tension? | Water striders |
| What is adhesion? | Attraction of water molecules to other substances |
| What types of substances attract water? | Polar and charged substances |
| What types of substances repel water? | Nonpolar substances |
| What is a solvent? | A substance that dissolves other substances |
| Why is water an excellent solvent? | It dissolves polar molecules and ionic compounds. |
| What does hydrophilic mean? | Water-loving; mixes with water |
| What does hydrophobic mean? | Water-fearing; does not mix with water. |
| Why is water's high specific heat important? | It helps stabilize temperatures. |
| What is high heat of vaporization? | Water requires large amounts of energy to evaporate |
| How does sweating cool the body? | Evaporation removes heat |
| Why does ice float? | Solid water is less dense than liquid water |
| Why is floating ice important for aquatic life? | It insulates water below and prevents lakes from freezing solid. |
| Into what ions can water dissociate? | H⁺ and OH⁻ |
| What is the pH of pure water? | 7 |
| What is an acid? | A substance that increases H⁺ concentration. |
| What is a base? | A substance that increases OH⁻ concentration |
| What pH range is acidic? | Below 7 |
| What pH is neutral? | 7 |
| What pH range is basic? | Above 7 |
| What is the pH range of human blood? | About 7.35–7.45 |
| What is the pH of stomach acid? | About 2 |
| What is a buffer? | A substance that resists changes in pH |
| What buffer does the pancreas release into the duodenum? | Sodium bicarbonate |
| Why does the pancreas release bicarbonate? | To neutralize acidic stomach contents |
| How much more acidic is Coca-Cola (pH 3) than water (pH 7)? | 10,000 times more H⁺ ions |
| What must all organic molecules contain? | Carbon and hydrogen |
| Is carbon dioxide organic? | No, it lacks hydrogen |
| Is water organic? | No, it lacks carbon |
| Why is carbon uniquely suited for life? | It forms four stable covalent bonds |
| What shapes can carbon skeletons form? | Chains, branches, rings, and helices |
| What are functional groups? | Groups attached to carbon skeletons that determine chemical behavior. |
| Give two examples of functional groups | Hydroxyl (-OH) and amino (-NH₂) |
| What are the four major biological macromolecules? | Carbohydrates, Lipids, Proteins, and Nucleic Acids |
| Which macromolecules follow a monomer-polymer pattern? | Carbohydrates, proteins, and nucleic acids |
| Which macromolecule does NOT follow a monomer-polymer pattern? | Lipids |
| Are lipids hydrophobic or hydrophilic? | Hydrophobic |
| What is dehydration synthesis? | Joining monomers by removing water |
| What is hydrolysis? | Breaking polymers apart by adding water |
| What elements make up carbohydrates? | Carbon, hydrogen, and oxygen |
| What is the typical carbohydrate ratio? | 1 : 2 : 1 (C:H:O) |
| What are the two major functions of carbohydrates? | Energy storage and structural support. |
| What is a monosaccharide? | A single sugar molecule |
| What is the most important monosaccharide for cellular energy? | Glucose |
| What is fructose? | Fruit sugar |
| What is galactose? | A component of milk sugar. |
| What sugar is found in RNA? | Ribose |
| What sugar is found in DNA? | Deoxyribose |
| What is a disaccharide? | Two monosaccharides joined together |
| What sugars form sucrose? | Glucose + Fructose |
| What sugars form lactose? | Glucose + Galactose |
| What sugars form maltose? | Glucose + Glucose |
| What is a polysaccharide? | A carbohydrate made of many sugars |
| What is starch? | Plant energy-storage polysaccharide |
| What is glycogen? | Animal energy-storage polysaccharide |
| Where is glycogen stored? | Liver and muscle tissue |
| What is cellulose? | Structural polysaccharide in plant cell walls |
| Why can't humans digest cellulose? | We lack the enzymes needed to break it down |
| What is the benefit of cellulose in the diet? | It acts as dietary fiber |
| What is chitin? | Structural polysaccharide found in arthropod exoskeletons and fungal cell walls |
| CHON stands for what four major biological elements? | Carbon, Hydrogen, Oxygen, Nitrogen |
| What determines an element's identity? | Number of protons (atomic number) |
| What determines whether an atom will bond? | The number of empty spaces in its valence shell |
| What type of bond holds water molecules together? | Hydrogen bonds |
| Why is carbon called the backbone of life? | It forms four covalent bonds and creates complex molecules |
| What process builds polymers? | Dehydration synthesis |
| What process breaks polymers apart? | Hydrolysis |
| What carbohydrate is stored by plants? | Starch |
| What carbohydrate is stored by animals? | Glycogen |
Created by:
jsminnie118
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