Evolution Blog

A fossil is formed through a long process. First of all, the organism must be dead. Its body is eaten by scavengers. The hard parts of the body such as bones can be remained and buried in sedimentary rocks. After millions of years of movement of the rocks and layers, older bones are buried in lower layers and newer remains are buried in upper layers. The fossils can be discovered on the surface of the earth by being weathering out from the wind, water, and sand.

Archaeologists and biologists use fossils as evidence for the Evolution theory. A theory is formed through a process with hypothesis, observation, evidence, and conclusion. Homology classification is created by observing similar structures of different organisms that can be used to conclude that they have common ancestors. Through millions of years of evolution in order to adapt to different living environments, organisms change their body structures even though they share common ancestor. Analogous structures have similar functions but the organisms have different body structures underneath the surface. For example, both a bird and a dragonfly have wings but their skeletons are different.

The evolution theory can be tested in the evidence of Tiktaalik, a type of fish that has certain amphibian characteristics. Different from the fish’s head, Tiktaalik’s head is flatter and its eyes are on the sides, allowing it to float above the water surface to look for prey. Tiktaalik’s limbs are different from fish’s fins in that they allow Tktaalik to go to shallow water area and not to be stuck, paving the way to becoming an amphibian animal.

Another method to test the Evolution theory is from biomedical evidence such as DNA and proteins in different organisms. Through comparing the Cytochrome C sequence in different organisms, we can draw a cladogram to see which organisms are closely related. The fewer differences in amino acid sequence, the more closely related the organisms are because the DNA mutations happen in less time and they are closer to their common ancestor.

Class 11 Quiz

1. This picture illustrates the evolution of whale. 55 million years ago, Mesonychid was a mammal that lived on land. Its four limbs allowed it to walk and hunt for prey. Ambulocetus evolved from Mesonychid. The structure of its head is flatter and its mouth was longer and sharper. The limbs of Ambulocetus adapted to amphibian environment that it was able to go to near land area yet still hunt in the water. The eyes of Ambulocetus were on the sides so that they can see better in the water. Rodhocetus evolved from Ambulocetus. The body structure of Rodhocetus was more streamlined, allowing it to swim in water. Its tail was divided into two parts to balance the body while swimming. The limbs changed to fins because fingers were not needed in water. Finally, Basilosaurus evolved from Rodhocetus. The structure of the body was more streamlined. All four of the fins grew smaller. The tail was longer so it can swim faster.

2. E

3. All three of the organisms have wings that enable them to fly. However, bats have finger structure in the wings, while birds only have one single limb in the wing and dragon fly almost none. The limbs of birds are more stronger than bats and dragonfly so that they can stand on their feet. The neck of bird is long so it allows the bird to pick up its prey and food from the ground. The bat has a short neck and the dragonfly does not have a long one either. The long tail of dragonfly allows it to balance its body while the bat and the bird don't need long tails.

4. The sequences of Cytochrome C of different organisms demonstrate the relationship between them. The fewer differences between two organisms, the more closer they are to the common ancestor because DNA mutations take place over time. The less time available for mutations to happen, the closer two organisms are to their more recent common ancestor. Between human and Rhesus monkey, there was only 1 difference in amino acid number. Therefore, human and Rhesus monkey are very closely related.

5. Homology provides the relationship between a pair of structures or genes that have the common ancestor. For example, modern toothed whale and rodhocetus have the same tail structures. Furthermore, Tiktaalik share some common traits with fish, such as streamlined body structure.

Class 6 Blog

In this class, we started with the structure of a cell.

A cell membrane is like a security wall that is selectively permeable.

Structure

• Bi-layered—Phospholipid (Hydrophobic and Hydrophilic)
• Protein is imbedded
• Cholesterol—Share fluid
• Carbohydrate (consists of CHO)
• Glycoprotein (Communicate—chemically talk)

Function

• 4 Functions of membrane proteins
• Transport—Water + HTP
• Enzymes
• Signal transduction
• Cell recognition

Osmosis

·      Movement of molecules

§  Hypotonic

§  Hypertonic

§  Isotonic

Diffusion

·      Movement of Substances

·      Concentration Gradient

§  Passive transport

§  Active transport

House Case

The process includes symptoms, tests, and diagnosis. List all the possible answers and conclusions on the board. Then, ask the patient questions that are related to the symptoms and potential conclusions. This activity requires the students to apply wide range of knowledge and ask the “right” questions.

Class 5 Blog

In the class, we continued the experiment on part 1 and started a new one. In part 1, the glucose and starch diffused into water. Therefore, the solution turned blue when a drop of iodine was added. The Benedict’s was used to test the presence of sugar in the solution. When the solution was heated and the Benedict’s was added, the solution’s color changed from blue to orange, confirming that there is sugar in the solution.

In the new lab, we had three cells. We measured the surface areas and put them each in a beaker and added KI solution. After a few minutes, the cell changed color and we cut them in halves. The biggest cell has less color spreading in the inside due to its size. Therefore, the smaller the cell, the faster diffusion takes place.

Class 4 Blog

Diffusion and Osmosis

Diffusion: Molecules travel from high concentration to low concentration.

Osmosis: Put the solution in a semi-permeable “cell” and dump the cell into water. If there are more water molecules in the cell, water molecules go from the cell to the water until equilibrium is reached. Vice versa.

Hypertonic: A solution that contains more solvent than solute.

Hypotonic: A solution that contains more solute than solvent.

Isotonic: A solution in which the solute and solvent are equally distributed.

Water potential: affected mainly by two factors—pressure and the amount of solute. Water always travels from high potential to low potential.

In Part 2 and Part 4 of the experiment, we proved the ranking of the molarity of the solutions through their percentage of mass change. And there is sugar in different kinds of athletic drinks.