Identifying Questions and Hypotheses

In this article NASA says that there are signs of water on Mars. The question is "Is it possible for there to be life on Mars?" The hypothesis is If there is water on Mars, then it is possible for there to be life on Mars. Scientists say that there are definite signs of liquid water on present day Mars. If there is water, there is life. This study can help build on the possibility of contemporary life on Mars. I knew that scientists were talking about people living on Mars before. I never knew that there was water on Mars.

http://www.nytimes.com/2015/09/29/science/space/mars-life-liquid-water.html?_r=0

Unit 2 Reflection

      This unit was about the chemistry of life.The first section was about atoms. It talked about protons, neutrons, and electrons.Subatomic particles that make up atoms are protons, neutrons, and electrons. A chemical element is a pure substance that consist entirely of one type of atom. Atoms of the same element that differ in the number of neutrons are isotopes. Because they have the same number of electrons, all isotopes of an element have the same chemical properties. A chemical compound is a substance formed by the chemical combination of two or more elements in definite proportions. An ionic bond is formed when one or more electrons are transferred from one atom to another. A covalent bond forms when electrons are shared between atoms. The molecule is the smallest unit of most compounds.Van der Waals forces are when molecules are close together and a slight attraction develops between the oppositely charged regions of nearby molecules.
      The second section was about the properties of water. It also talked about valence electrons and why carbon was so versatile. Carbon is very versatile because it was four valence electrons. It can bond with different elements easily. Water is polar because there is an uneven distribution of electrons between the oxygen and hydrogen atoms. Cohesion is an attraction between molecules of the same substance. Adhesion is an attraction between molecules of different substances. A mixture is a material composed of two or more elements of compounds that are physically mixed together but not chemically combines. All components of a solution are evenly distributed throughout the solution. A solute is the substance that is dissolved. A solvent is the substance in which the solute dissolves. The mixture of water and non dissolved material is called suspension. Buffers are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.
      It also talked about carbohydrates, lipids, proteins, and Nucleic acids. Proteins are made up of amino acids. It also talked about what an acid and base were. The topics about proteins was the most confusing. I feel like I pretty much understand everything about atoms, but not macromolecules. Different enzymes work better in different conditions of pH and temperature.Smaller units called monomers, join together to form polymers. Carbohydrates are compounds made up of carbon, hydrogen, and oxygen atoms, usually a ratio of 1:2:1. Living things use carbohydrates as their main source of energy. Plants and some animals also use carbohydrates for structural purposes. Lipids are made mostly of carbon and hydrogen atoms. Lipids can be used to store energy Some lipids are important parts of biological membranes and waterproof coverings.

Cheese Lab Conclusion

Time to Curdle (minutes)
Curdling Agent:	chymosin	rennin	buttermilk	milk (control)
Acid	5	5
Base
Cold
Hot	5	10
Temp control	15	15
pH control	15	10

In this lab we asked the question, what are the optimal conditions and curdling agents for making cheese? We found that hot and acidic conditions with chymosin were the best for curdling cheese. The time in acids was only 5 minutes for both chymosin and rennin. Buttermilk and milk both didn’t curdle within 15 minutes. In hot environments for chymosin it only took 5 minutes to curdle as well and 10 for rennin. Since rennin comes from a calfs stomach, warmer and more acidic environments are better for curdling. This data supports our claim because acidic and hot temperatures made the cheese curdle the fastest.

While our hypothesis that warmer and more acidic conditions with chymosin with make cheese curdle faster, there could have been errors due to how the lab was set. We checked to see if it curdled every five minutes, but the acid ones might have curdled even faster than 5 minutes. This would have affected the data. It might have shown that chymosin was faster than rennin.  Another data we might have made is when we were measuring how much curdling agents to put into the milk. The medicine droppers had air bubbles in them and it was hard to measure them exactly. Because of that, each test tube had different amounts of curdling agent. Due to these errors, in future experiments I would recommend for us to be more careful and check ever two minutes rather than five.

This lab was done to demonstrate chemical reactions. From this lab I learned that different conditions would affect the results which helps me understand the concept of chemical reactions. Based on my experience from this lab, I know that warmer and more acidic environments would help cheese curdle faster.     

Sweetness Lab

      The question was how does the structure of a carbohydrate affect its taste. Monosaccharides were all sweet. Glucose, fructose, and galactose were all very sweet, there degree of sweetness are all over 100. Disaccharides such as maltose and lactose, were less sweet in the 50s-70s range. Except for sucrose, they all werent that sweet. Polysaccharides were pretty much tasteless. Starch and cellulose are all in the 20s and lower.  Fructose is found in fruits and honey so it was expected that it would be sweet. Sucrose is basically table sugar so it was pretty sweet as well.
      Monosaccharides  are major fuel for cellular work. Disaccharides are a nutritional source for monosaccharides. Polysaccharides can be used for storage or as building materials for the cell or the whole orgamism.
      The rating for the sweetness might be different for different people because everyone has different taste buds. One person might find something super sweet while the other finds it normal. Tasters could rank the same samples differently because every ones taste buds are different.

                  

Characteristics of Life