Friday, September 19, 2008

Evolution Connection!

This is the first post of two different types I will frequently post on the blog. One type of post is on Evolution Connection-- A major theme in AP Biology. The other type of question is on Science, Ethics and Technology.

For those of you wanting to stretch yourself, I am posting two questions which relate to chapter 6 on the cell. If you would like to "answer" these questions, please do so by posting a response. Please remember that there can be many answers.

1. Which aspects of cell structures best reveal evolutionary unity?

2. What are some examples of specialized modifications?

Have Fun!


Ruby said...

1. DNA is one of the major aspects of cell structures that reveal evolutionary unity because ALL life forms (and so all cells) have the same nucleotides (A, T, C, G). The SAME DNA is used (though the nucleotides may be sequenced differently) to preform cellular functions.

2. Some examples of specialized modifications are plasmodesmata, chloroplasts and the central vacuole which are all specific to the plant cell. Lysosomes and centrosomes are examples of specialized modifications specific to animal cells.

- Ruby

Ruby said...

A good site for what we are covering is

This site talks about both the animal cell and plant cell (as well as bacteria, virus structure, microscopy, etc.)

Leigh said...

1. Like Ruby said, DNA is apart of all life forms so that does contribute to the unity of living things. Also, the means of taking in energy is unifying. Even though different types of cells do this in different ways, all cells need ATP in order to survive.

2. Going along with the taking in energy idea, chloroplasts are specific to plant cells. Plants take in the suns energy to provide energy for themselves. So chloroplasts are definately specialized for the plant cell. Also, the shape of plant cells help define their shape and helps the plant to be sturdier.

Oh and thanks for the website Ruby!

morgan flynn said...

1.The plasma membrane, and DNA are parts of cells that best show evolutionary unity:
-Prokaryotes and Eukaryotes both have plasma membranes. They are absolutely necessary because they are the structures that hold the cells together. Cells would not exist if it were not for their plasma membrane barriers that separate them from all other cells. The evolution of plasma membranes was a turning point because it suddenly opened up whole new possibilities for life on Earth.
-DNA also shows evolutionary unity because, again, all cells (prokaryotic and eukaryotic) have DNA. Without the genetic instructions for making cells, life would not exist.

2. Vacuoles are examples of specialized modifications:
-Central vacuoles are key for a plant to uphold its hypotonic state. The water and other molecules the central vacuole holds keep the plant from wilting and dying. Vacuoles also store pigments, keep reserves of important organic compounds (like proteins), and occasionally contain poisons that keep predators away from plants. In plants and fungi that lack lysosomes, vacuoles have been modified to carry out hydrolysis.
-Contractile vacuoles are immensely important in the way that they pump excess water out of freshwater protists that would otherwise be unable to keep a stable concentration of molecules and fluid.

emmasters said...

I was wondering if there was any correlation between mitochondria DNA and the DNA located in the nucleus but could only find one contradictory article on Wikipedia. Is there any way that these two could be linked to evolution from a bacterial origin?

HannahMontana said...

1. DNA is best structural aspect that reveals evolutionary unity between all living organisms, both eukaryotes and prokaryotes. DNA allows all living things to function, grow, and reproduce, will are all necessary for survival of life. DNA is a nucleic acid that contains genetic instructions regarding the development of loving things. The same sequence of nucleotides (Adenine and Thymine bond together; Guanine and Cytosine bond together). In cells, DNA forms chromosomes by the process of DNA replication (transcription and translation of RNA to form DNA). Mitosis and/or Meiosis contribute to growth and reproduction.

2. Photosynthesis is an evolutionary chemical phenomena of plants. Plants weren't always on land, they used to be fully immersed in water and thus got water and nutrients from the ocean floor. As plants evolved, they began growing near the shoreline so it would be easy to obtain water. Plants eventually adapted to survive on dry land with specialized modifications of a vascular system which includes chloroplast, xylem, phloem, and a central vacuole. The chloroplasts are green structures that are responsible for photosynthesis: converting light energy from the sun into chemical energy to supply nutrients for the plant. The Xylem and Phloem are transport vessels for water and nutrients as well as transpiration. The large central vacuole supports the plant and prevents the drying out of wilting of the plant. It also provides a storage system for pigments and other organic compounds. Animal cells contain lysosomes which digests things as well as centrosomes which organizes microtubules.

Alyssa Hamilton said...

2. Some examples of specialized modifications in plant cells are the plasmodesmata, central vacuoles, and the cell wall. Lysosomes, centrosomes, centrioles, and the flagella are specialized modifications of animal cells.

Alyssa Hamilton said...

1. The plasma membrane and DNA are aspects of evolutionary unity. This is because both types of cells prokaryotes and eukaryotes have plasma membranes. These membranes are vital to the cell structure this is what holds the cells together. The cell membrane separates the cell from other cells allowing for evolutionary unity.
DNA is as another aspect of evolutionary unity because it is consistently found in all parts of living organisms. It is what genetically makes everything different in their existence. The same nucleotides exist in prokaryotes and eukaryotes, but there can be many variations in their sequence (A,T,G,D) performing cellular functions.

SMABiology said...

Love the website that Ruby found. I go to this web site a lot, especially since it is from my undergraduate alma mater! A great biological science department! Your responses are great. Questions like this make you critically think as well as form connections between what we are studying and the bigger picture.

WhitHar said...

1. Which aspects of cell structures best reveal evolutionary unity?

DNA and plasma membranes are aspects of cell structure which best reveal evolutionary unity. These two aspects keep all cells alive and functioning. Without either one, a cell would die. DNA is found in all cells (prokaryotes and eukaryotes), and thus all life forms. Plasma membranes are also found on all cells. DNA uses genetic instructions to tell the cell to form and maintain a plasma membrane and the membrane holds the cell together so that it can be a functioning unit.

2. What are some examples of specialized modifications?

Intercellular junctions are localized modifications of the plasma membrane which occur in adjacent animal cells. There are three specific kinds of intercellular junctions: tight junctions, desmosomes, and gap junctions.

tight junction-intercellular junction that holds cells together tightly enough to block transport of substances through the intercellular space.

desmosomes- intercellular junctions that rivet cells together into strong sheets, but still permit substances to pass freely

gap junction-intercellular junction specialized from material transport etween the cytoplasm of adjacent cells.

Kicki said...

1. The aspects of cell structure that best reveal evolutionary unity are the plasma membrane and DNA. Both os these aspects of a cell play an essential role in the cell's function. DNA holds the genetic information of a cell, and therefore plays a fundamental role in the reproduction and functioning of the cell. DNA is also found in all types of cells (prokaryotes and eukaryotes). Thus DNA plays a primary role in all life forms today. In addition, the plasma membrane is found in both eukaryotic and prokaryotic cells. The plasma membrane encloses the interior of a cell, and provides for the cell's basic structure.