Masoumehhonorsbiology



Part I : Bonding

Answer the following questions:

1- Draw 4 water molecules and show the hydrogen bonds between them.

2- Dissolve NACL in the water and show the ions interactions in the above model you created.( you can use internet or your ebook to find the answer)

Go through the following link and answer the below question.



1- Why salt is added to the snow on roads in snowy days?

Part II : Biological molecules

Read the following text and answer the questions:

The Building Blocks of Life

Our bodies are amazing. They are constantly working hard to keep us alive and well. Most of the processes that do this occur without us even noticing, but that doesn't mean that they're not important. One of the coolest things our cells do is make an incredible number of larger molecules from a very limited set of smaller ones.

That's right; the complex diversity of life on Earth really comes from just a small number of building blocks, which fall into four main classes: carbohydrates, proteins, lipids and nucleic acids. These are considered macromolecules because they are molecules that are very large on a molecular scale. And large means large - some of them consist of thousands of atoms, all made by your cells!

Most macromolecules are made by joining together small molecules called monomers. This literally means 'single unit' ('mono' means 'one'), and these are the single-unit molecules that combine to form polymers. What are polymers? Simply put, they are chains of monomers. This makes sense because 'poly' means 'many.'

Monomers can join together to make polymers, and polymers can break apart into monomers. There are unique reactions that occur in our bodies to do this. Dehydration reactions are those that link monomers together to form polymers, and hydrolysis breaks polymers apart into monomers.

Dehydration Removes Water

When you are thirsty, it's your body's way of telling you to drink some water because you are dehydrated. Just like a dehydration reaction, you've lost water. Dehydration reactions are named as such because as the monomers are linked together, a molecule of water is released. This happens because on one end of a monomer is a hydrogen atom (-H) that is just waiting to bind with a hydroxyl group (-OH) on another monomer.

When they come together, the hydrogen and hydroxyl groups join together like long-lost friends and break free of their monomers. And what do we get when we have two H atoms and one O atom? H2O, which is water! As the water molecule breaks free, the two monomers link together to make a polymer.

Dehydration reactions are what build your DNA, which is your unique and identifying genetic code. Your DNA is built from just four kinds of monomers called nucleotides. Since all of us have the same monomers to build DNA from, it's the arrangement of the monomers that makes each of us unique. As you can see, with more than seven billion different individuals in the world, the number of possible combinations is enormous.

Hydrolysis Breaks With Water

When you are dehydrated, you remedy this by hydrating - you add water to your body to rehydrate yourself. Hydrolysis, which is the reverse of a dehydration reaction, works the same way. In these reactions, polymers are broken apart by adding a water molecule and separating the polymer back into monomers. Remember that friendly water molecule from before? Well, the -H and -OH appear to need some alone time now, so they hook up with a polymer and go their separate way with a new monomer. The -H attaches to one monomer and the -OH goes off with another.

Hydrolysis is an important part of how your body breaks food into its nutritious components. The food you eat enters your body in the form of polymers that are far too large to be used by your cells, so they must be broken down into smaller monomers. You digest them by hydrolysis, breaking them apart with water molecules.

Enzymes Aid Both Reactions

Both dehydration reactions and hydrolysis need help, which they get from enzymes. These are specialized macromolecules that speed up chemical reactions in cells. Have you heard the term 'lactose intolerant'? This refers to people who are not able to hydrolyze (break apart) the bond in lactose, which is a sugar found in milk. The enzyme lactase is responsible for helping hydrolyze the lactose polymer, and people without it are not able to digest this sugar, causing them to have an upset stomach when they drink milk.

Questions:

1- Draw a diagram to show a disaccharide and a mono saccharide to make polysaccharide.

2- Draw a diagram to show two amino acids making dipeptide.

3- What is the molecular formula for a polysaccharaide formed of 5 glucose molecules knowing that the formula of one glucose molecule is C6H12O6?

Part III: water properties :

Go to the following link to learn more about water properties:



and answer the following questions:

1-Why is the latent heat of vaporization of water greater than the latent heat of fusion of water?

2- Analyze the following graph:

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Part IV Enzymes

Go to the following link ( 3 pages) to answer the following questions and do the online test. Write your score on the paper.





1- Draw two pictures to show anabolic and catabolic reactions in enzymes.

2- What are enzymes? Explain their primary structure.

3- Analyze the following graphs by writing a small paragraph for each one.

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AP Students only

Part V: Experiment/analytical based questions

Read the following text and answer the question:

Questions :

1- Differentiate between endotherms and ectotherms .

2.

Birds and mammals; maintaining their body temperature within a narrow range by heat generated by metabolism; high-energy strategy that permits intense, long-duration activity of a wide range of environmental temperatures.

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3.

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What Is an Endotherm?

You might not know it yet, but you are an endotherm. So is your dog, Fluffy, and your cat, Whiskers. The birds flying over your house are even endotherms. So, it seems everyone is an endotherm, right? Nope.

Birds and mammals are endotherms, whereas the goldfish swimming in your fishbowl, the lizard basking in light of the heat lamp, and the frog swimming in your tank are not endotherms. So, what is an endotherm?

The word endotherm is Greek and literally translates into 'within temperature,' which means endotherms are critters that control their own body temperature. The goldfish, lizard, and frog are ectotherms, which translates into 'outside temperature,' meaning their environment controls their body temperature.

The words endotherm and ectotherm sound a lot alike, so it is a good idea to come up with a way to remember the difference. The word endotherm sounds like in-do-therm, which will help you remember that endotherms regulate their body temperature from inside.

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How It Works

You may not realize your body is constantly regulating your temperature, but you certainly have noticed some of the effects. Your central nervous system tells a section of your brain, the hypothalamus, to regulate body temperature through sweating, blood vessel dilation and constriction, and shivering.

When you get cold, your body shivers to generate heat, and you may become pale because blood vessels called capillaries constrict to avoid heat loss. Your body may tell your thyroid, a gland in your neck, to increase your metabolism, which will increase your body temperature. When you get too hot, your body sweats, and your skin may become red and flushed because capillaries dilate to release heat.

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Fluffy, Whiskers, and the birds flying over your house are able to maintain their body temperature in much the same way as you with a few exceptions. Fluffy, Whiskers, and the birds are covered with fur or feathers, so they pant. Birds do not sweat, but Fluffy and Whiskers sweat through their feet.

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Endotherms Vs. Ectotherms

Due to their ability to regulate their own body temperature, endotherms can be found all over the world. Ectotherms, on the other hand, have a more limited habitat because they must depend on their environment. For example, in the northern parts of Alaska, there are no reptiles and only one species of frog, but there are numerous species of mammals and birds.

Maintaining a constant body temperature requires a lot of energy, so endotherms must continually eat whereas ectotherms can go days without food. Because endotherms have a faster metabolism compared to ectotherms, they are able to have larger brains. Larger brains allow endotherms to have complex behaviors not seen in many ectotherms.

Finally, because endotherms maintain a constant body temperature, their body cannot withstand extreme temperature fluctuation. If an endotherm's body becomes too hot or cold, it will die. An ectotherm, on the other hand, is designed to withstand a wide temperature range, so if it gets too cold or too hot, the ectotherm will survive.

Stanley and miller experiment :

Go to the following link to get more idea about the experiment.



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