Unit 1 ~ Learning Guide

Transcription

1 Unit 1 ~ Learning Guide Name: INSTRUCTIONS Complete the following notes and questions as you work through the related lessons. You are required to have this package completed BEFORE you write your unit test. Do your best and ask questions about anything that you don't understand BEFORE you write the unit test. U1: INTRODUCTION (video) Homeostasis: Examples: 1. Blood Glucose Concentration remains about 0.01% 2. PH of blood is always near 7.4 (slightly basic) 3. Blood pressure in the brachial artery averages near 120/80 4. Blood temperature averages ~ 37 C 5. Pancreatic Juice (ph 8.5) neutralizes stomach acids so that food entering the small intestine is basic. 6. CO 2 concentration in our blood stimulates our breathing. Negative Feedback: Control centers in the _that cause specific body reactions. Once normalcy is reached, the is NO LONGER stimulated. (This is why the process is called _) 1

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3 Positive Feedback: Instead of achieving normalcy, Negative Feedback tends to a system. Positive Feedback leads to. 3

4 U1: INTRODUCTION 1. A woman is being tested for diabetes mellitus. Her blood glucose levels are measured and recorded over a period of time (data given below). Please graph the data and answer the associated questions. Graphing Tips: q the independent variable is always placed on the x-axis (in this case, time) q the dependent variable is always placed on the y-axis (in this case, blood glucose levels as they are dependent on the time) q each axis needs an informative title that includes units of measurement such as hours and mg/dl q the graph needs an informative title q each square on the graph must represent a consistent value such as 1 hour (xaxis) or 20 mg/dl (y-axis) Table 1. Blood Glucose Levels in Patient X over Time. Time (h) Blood Glucose Levels (mg/dl) Figure 1. Blood Glucose Levels in Patient X over Time 4

5 a. The normal range for blood glucose levels is mg/dl. Does Patient X always remain within the normal range? b. Does Patient X have any apparent problems with glucose regulation? Why or why not? c. Which type of feedback mechanism (positive or negative) is used to regulate blood glucose levels? Explain your reasoning. 5

6 U1: WATER (web notes and video) Water The Universal Solvent Because water is the substance that makes life possible as we know it on Earth, astronomers hope to find evidence of water on newly discovered plants orbiting distant stars. Life on Earth began in the water and evolved there for 3 billion years before spreading onto land. Background Information Terrestrial organisms are still tied to water. In fact, most cells are surrounded by water and cells themselves are about 70-95% water. Life as we know it, is based on the. To be "organic" a molecule must have a carbon atom in it. For example, vinegar (CH 3 CH 2 OH) is organic, whereas is not. The organic molecules in living things are easily grouped into four types. Understanding these four biochemicals is the focus of Unit 2. If Not Organic, Why is Water so Incredibly Important? What happens to the quality of life if the chemical conditions of living things change? In the formation of, atoms must bond together to form. In order to do this, the around the various nuclei in the compound must also be stable. This stability can be achieved through some degree of between the atoms. If the atoms share the electrons reasonably equally, their association is termed bond. 6

7 Ionic Bonds The alternative is a very unequal sharing of electrons. This is called an where it seems as though one atom actually gives. Neutral atoms become when they lose electrons and when they gain electrons. In between these two extremes is what is termed. Polar covalent molecules have (regions with slight positive and negative natures). A water molecule is an example of this kind of molecule. Structure of Water In a covalent bond atoms to become stable. If the electrons in a covalent bond are not shared equally by the two atoms, the molecule is then called a. 7

8 Polar Molecule Any molecule that has a different charge on two ends (asymmetrical) is called a molecule. One charge being the negative dipole the other being the positive dipole. Therefore, water molecules behave as with one another. causes water to have some degree of structure that extends beyond the individual molecules and cause a community water effect. The overall property is called, i.e. the attraction of the This means that water molecules are to one another. The negative charge on the oxygen attracts the positively charged hydrogen some distance away to produce a weak bond called a. YOU SHOULD WATCH THE STRUCTURE OF WATER VIDEO BEFORE PROCEEDING ANY FURTHER! Hydrogen Bonding Although hydrogen bonds are weak, the vast number of these bonds gives water its unique properties. Each water molecule can form hydrogen bonds with up to neighbors. 8

9 Water is the Solvent of Life A is a mixture of one or more soluble substances, called, dissolved in a liquid called the. A sugar cube in a glass of water will eventually dissolve to form a uniform mixture of sugar and water. The dissolving agent is the and the substance that is dissolved is the. In our example, water is the solvent and sugar the solute. Can you identify the solvent and solute in each of the following solutions? Example 1: 15 g baking soda and 100 ml of water? Solvent: Example 2: Nail polish removed by acetone? Solvent: Example 3: 1.00L ethylene glycol and 875 ml water? Solvent: Example 4: Chromium dissolved in hydrochloric acid? Solvent: Solute: Solute: Solute: Solute: Some Key Properties of Water Include: 1. Water acts as a Solvent Water and is able to dissolve many chemical substances especially other. Since blood is mainly water, the ability of water to dissolve and transport substances greatly aids in bringing about necessary. 2. Water acts as a Temperature Moderator Water moderates temperature and climate (both internal and external climates). Water can absorb a great deal of. Water also releases heat slowly. This property is referred to as a As a liquid evaporates the most energetic molecules are carried away leaving. 9

10 the lower kinetic energy molecules behind which cools the surface of the liquid that remains -. Internal example - External example - Oceans keep surrounding land masses cool in summer and warmer in winter. 3. Water has a "weird" Density Liquid water is than ice (very rare for compounds). Most materials contract as they solidify, but water expands. Therefore, ice forms on top of water levels. This oddity has important consequences for life. If ice sank, eventually all ponds, lakes, and even oceans would freeze solid. During the summer, only the upper few inches of the ocean would thaw. Instead, the surface layer of ice insulates liquid water below, preventing it from freezing and allowing life to exist under the frozen surface. 4. Water is Transparent Light organisms below. 5. Water is Cohesive/Adhesive Water molecules keeps surfaces. This 10

11 Diffusion of gases occurs much more efficiently moist surfaces. (sticking to each other) among water molecules plays a key role in the transport of water against gravity in plants., is a measure of the force necessary to stretch or break the surface of a liquid and is related to cohesion. Water has a than most other liquids because hydrogen bonds among surface water molecules the surface. Water behaves as if covered by an invisible film. Some animals can on water without breaking the surface. (clinging of one substance to another) contributes too, as water adheres to the walls of the blood vessels. ****Note: Focus on the properties of water that apply to the human body.**** YOU SHOULD WATCH THE FUNCTION OF WATER VIDEO BEFORE PROCEEDING ANY FURTHER! What are four important functions of water in the human body? Example 1: Example 2: Example 3: Example 4: 11

12 U1: WATER 1. Sketch a ball and stick diagram of a water molecule. Label the atoms and indicate the partial charges that exist in a water 2. What type of bonds are found between hydrogen and oxygen atoms within a single water molecule? 3. What type of bonds form between two or more water molecules? 4. Use a diagram with 5 water molecules to illustrate hydrogen bonding between water molecules (start with one molecule in the middle). How many water molecules can hydrogen bond with a single water molecule? 12

13 5. List 3 everyday examples of the cohesive and/or adhesive properties of water. 6. Water is a molecule. Water many substances (especially other molecules). This property makes water an excellent. 7. Use several examples each to explain how water is essential to life on Earth as we know it with respect to the following properties: a. Water acts as a Solvent b. Water acts as a Temperature Moderator c. Water acts as a Lubricant and Transportation Facilitator 13

14 8 Please indicate whether the statements below are true or false. Please correct any false statements. T / F a. Water molecules can attract other water molecules by hydrogen bonding. T / F b. Hydrogen bonds are stronger than ionic or covalent bonds. T / F c. The majority of our cellular reactions occur in water. T / F d. Large lakes and oceans tend to moderate local temperatures. T / F e. Water is an organic molecule. U1: ph, ACIDS AND BASES (web notes and video) ph Organisms are sensitive to changes in ph ( ). Acids An is a substance that in a solution. For example when hydrochloric acid is added to water, hydrochloric acid dissociates to form hydrogen ions and chloride ions: HCL à H + + Cl - The addition of H + makes a solution more acidic. 14

15 Bases A base is a substance that increases the hydroxide ion concentration in a solution. For example when sodium hydroxide is added to water, sodium hydroxide dissociates to form sodium ions and hydroxide ions: NaOH à Na + + OH - Solution with more The ph scale is used to describe how (the opposite of acidic) a solution is. are basic solutions. YOU SHOULD WATCH THE ACID AND BASES VIDEO AND THE ph SCALE VIDEO BEFORE PROCEEDING ANY FURTHER! ph Scale The ph scale, ranging from 1 to 14, compresses the range of concentrations by employing logarithms. In other words every number on the ph scale is a multiple of 10. ph = -log [H + ] or [H + ] = 10 -ph A ph of 7 is a neutral ph where the - [OH - ]. [H + ] = A ph that ranges between 7 and 14 has more hydroxide ions than hydrogen ions making it a basic solution and a ph that ranges between 1 and 7 has more hydrogen ions than hydroxide ions making it an acidic solution. W e can calculate the the difference in hydrogen ion concentrations at different ph levels by multiplying or dividing by 10. For example a ph 6 has more H + than at ph 7. A ph of 3 has more H + than ph 5 and so on. Try the following ph comparisons: Example 1: ph of 14 has less H + than a ph of 12 Example 2: ph of 6 has more H + than a ph of 11 The ph scale is just a comparison between the [H + ] and [OH - ]. 15

16 YOU SHOULD WATCH THE SECOND ph SCALE VIDEO and THE BUFFERS BEFORE PROCEEDING ANY FURTHER! Buffers Most which control the in your body, can only operate at certain levels. If ph levels change too drastically these biochemicals will denature (lose their shape) and no longer function properly. Example: Blood must be at a ph close to or else we may become ill. At the wrong ph the blood cannot transport as efficiently. As you can see then the can be disrupted by changes to the H + and OH - concentrations away from their. To maintain cellular ph values at a constant level,. The function of Buffers is to when H + or OH - is added to the solution. 16

17 Buffers are. Buffers accept hydrogen ions from the solution when they are in excess and donate hydrogen ions when they have been depleted The buffer keeps ph constant. Acids are molecules that dissociate to release ions. In this respect water acts as a. HCI on the other hand is a because it dissociates to a much greater extent. Systems with HCI in them have a lot of free floating around. Bases are molecules that release. Molecules like. Bases have a because the H+ in an acidic environment will combine with OH- from a base and form. YOU SHOULD WATCH THE DEMONSTRATIONS OF BUFFERS AT WORK VIDEO BEFORE PROCEEDING ANY FURTHER! Note: The first graph shows ph change without a buffer, while the second graph shows ph change with a buffer. U1: ph, ACIDS AND BASES 1. Please define the following terms a. acid b. base 17

18 c. ph d. buffer 2. Indicate whether the following ph values represent an acidic, basic or neutral solution. a. ph 0: b. ph 12: c. ph 7: d. ph 3: 3. Hydrochloric acid (HCl), a strong acid, is added to a beaker of pure water: a. What is the ph of the pure water in the beaker before the acid is added? b. How does the hydronium ion concentration change after the acid is added? c. What happens to the ph of the solution in the beaker as the acid is added? 4. How much has the hydrogen ion concentration changed in a solution if its ph value goes from 6 to 4? Remember to indicate whether this change represents an increase or decrease in hydrogen ion concentration. 18

19 5. ph balance is very important to biological systems. a. Why? b. What prevents rapid or large changes in ph in biological systems? c. Give an example of where ph balance is important and regulated in a living organism. ~ END OF BIOLOGY 12 UNIT 1 LEARNING GUIDE ~ 19

20 UNIT 1 ANSWER KEY U1: INTRODUCTION 1. A woman is being tested for diabetes mellitus. Her blood glucose levels are measured and recorded over a period of time (data given below). Please graph the data and answer the associated questions. a. The normal range for blood glucose levels is mg/d. Does Patient X always remain within the normal range? - Yes ranges from mg/dl b. Does Patient X have any apparent problems with glucose regulation? W hy or why not? - No blood glucose levels appear to remain within a normal range suggesting homeostatic mechanisms are functioning correctly to regulate blood glucose levels c. W hich type of feedback mechanism (positive or negative) is used to regulate blood glucose levels? Explain your reasoning. - negative feedback loop as the process is maintaining normalcy (blood glucose between mg/dl) as opposed to moving levels towards an extreme as would a positive feedback loop 20

21 U1: WATER 1. Sketch a ball and stick diagram of a water molecule. Label the atoms and indicate the partial charges that exist in a water molecule. (2 marks) 2. W hat type of bonds are found between hydrogen and oxygen atoms within a single water molecule? (1 mark) - Covalent bond (intramolecular) 3. W hat type of bonds form between two or more water molecules? (1 mark) - Hydrogen bond (intermolecular) 4. Use a diagram with 5 water molecules to illustrate hydrogen bonding between water molecules (start with one molecule in the middle). How many water molecules can hydrogen bond with a single water molecule? (3 marks) 4 water molecules can hydrogen bond with a single water molecule 21

22 5. List 3 everyday examples of the cohesive and/or adhesive properties of water. (3 marks) - answers may vary but may include; o movement of water up plant stems o the ability of water bugs to "stand" on water o water clinging to a surface such as blood vessels 6 Water is a polar molecule. W ater dissolves many substances (especially other polar molecules). This property makes water an excellent solvent 7 Use several examples each to explain how water is essential to life on Earth as we know it with respect to the following properties: a. Water acts as a Solvent - dissolves charged and polar molecules such as salts which can then be transported throughout the body - dissolves charged such as salts that can then react with one another to form new ionic compounds b. Water acts as a Temperature Moderator - the polarity/hydrogen bonding of water makes it slow to heat and cool meaning that it helps to maintain a relatively constant body temperature and global temperature - the polarity/hydrogen bonding of water also results in it having a high heat of evaporation making it (in the form of perspiration) an effective coolant on the surface of the skin c. Water acts as a Lubricant and Transportation Facilitator (3 marks) - the polarity/hydrogen bonding of water makes it cohesive/adhesive such that it fills and flows through vessels easily making it an effective transport medium - the polarity/hydrogen bonding of water allows it to remain in a liquid state at body temperature 9as opposed to a gas as is comparable for most similar molecules) making it an effective transport medium - the polar nature of water allows it to stick to other surfaces (adhesion) which provides lubrication required for the movement of joints, blinking of eyes etc. 22

23 8 Please indicate whether the statements below are true or false. Please correct any false statements. T / F a. Water molecules can attract other water molecules by hydrogen bonding. T / F b. Hydrogen bonds ions are weaker than or covalent bonds. T / F c. The majority of our cellular reactions occur in water. T / F d. Large lakes and oceans tend to moderate local temperatures. T / F e. Water is an organic molecule. U1: ph, ACIDS AND BASES 1. Please define the following terms (4 marks): a. Acid = compound that releases hydrogen ions in aqueous solutions (increase H + ions in solution) b. Base = compound that releases hydroxide ions in aqueous solutions (increase OH - ions in solution) c. ph scale = describes how acidic or basic a solution is, a negative log scale referring to the concentration of hydrogen ions (H + ) within a solution d. buffer = a substance that resists changes in ph despite the addition of an acid or base 2. Please indicate whether the following ph values represent an acidic, basic or neutral solution. a. ph 0: acid b. ph 12: base c. ph 7: neutral d. ph 3: acid 23

24 3. Hydrochloric acid (HCl), a strong acid, is added to a beaker of pure water a. W hat is the ph of the pure water in the beaker before the acid is added? - by definition the ph of pure water is 7 (neutral) b. How does the hydrogen ion concentration of the solution in the beaker change does after the acid is added? - by definition acids increase the hydrogen ion concentration of a solution c. W hat happens to the ph of the solution in the beaker as the acid is added? - ph decreases 4. How much has the hydrogen ion concentration changed in a solution if its ph value goes from 6 to 4? Remember to indicate whether this change represents an increase or decrease n hydrogen ion concentration. Thus, the hydrogen ion concentration has increased a 100 fold when ph shifts from 6 to ph balance is very important to biological systems. a. Why? - Because many cellular activities require the action of enzymes which are proteins whose three-dimensional structures and accompanying functions are dependent on a particular ph changing the ph changes the structure and inhibits the enzyme's functions and therefore, inhibits cellular activities b. W hat prevents rapid or large changes in ph in biological systems? - buffers c. Give an example of where ph balance is important and regulated in a living organism. - Answers may vary but may include; o o o in the blood (ph ~7.4) to maintain protein structure such as that of hemoglobin regulated using the bicarbonate buffer system and hemoglobin itself in the stomach (ph ~ 2) to ensure activation of digestive enzymes such as pepsin while also beginning to denature (unfold) ingested proteins regulated by parietal cells that release hydrochloric acid in the small intestine (ph ~ 7) to ensure the activation of digestive enzymes such as trypsin regulated by bicarbonate released into the small intestine by the pancreas 24