Midterm 1 Flashcards
What are the 5 characteristics of living things?
- Organized (cell is smallest unit of life)
- Reproduce, grow, and develop (DNA is signature molecule of life)
- Need and acquire energy (build, repair, multiply)
- Maintain homeostasis
- Evolve (change in genetic makeup overtime)
What is homeostasis?
A state of internal consistency maintain through a narrow range of variables. This range varies from one life-form to another.
What is adaptation?
Inherited characteristics (coded in DNA) allowing organism to survive and reproduce. Survival depends on adapting to current, local conditions.
Describe the steps of the scientific method.
- Make observation and ask a question
- Propose an explanation (hypothesis)
- Come up with prediction (if-then)
- Design and conduct experiment
- Analyze results and conclude
- Publish findings
Describe the components of experimental design.
- Sample size
- Variables
> Independent: manipulated variable (nutrient level)
> Dependent: response variable (growth)
> Standard: same for all specimens
> Control: basis for comparison (no nutrient) - Experiment must be repeatable by others and achieve similar results
What are the four main organic molecules and what are the monomers and polymers of each?
carbohydrates
- monomer: monosaccharide (glucose, fructose)
- polymer: disaccharide (sucrose), polysaccharide (starch)
lipids
- monomer: fatty acid
- polymer: triglyceride
nucleic acid
- monomer: nucleotide
- polymer: Deoxyribonucleic Acid (DNA) or Ribonucleic Acid (RNA)
proteins
- monomer: ammino acids (20 total)
- polymer: polypeptide chain (a.k.a proteins)
Describe the difference between a hypothesis and theory.
Hypothesis is tentative, narrow focused explanation of natural world. Must be testable and able to be disproved (falsifiable). Hypotheses can never be proven, only supported or rejected - new tech or questions could lead to different results!
Theory is well proven explanation that everyone generally accepts or regards as true. It is the best we have at explaining natural phenomena. Theories can help explain facts.
What is the difference between simple and complex carbohydrates and how do living organisms use carbohydrates?
Simple carbohydrates are easy to break down and give fast energy. Complex carbohydrates take longer to breakdown and provide a more stable energy source.
Living things use carbohydrates as a source of energy. Plants use carbohydrates in the form of cellulose for structure as well.
What is the difference between saturated and unsaturated fats?
Saturated fats are full of hydrogen and contain straight fatty acids, allowing more fatty acids to be packed tightly together. Saturated fats tend to be solids at room temperature and derived from animals.
Unsaturated fats contain less hydrogen and contain crooked fatty acids, allowing fewer fatty acids to be packed together. Unsaturated fats tend to be liquid at room temperature and derived from plants.
What does it mean to be “hydrogenated”?
Hydrogenation is the addition of hydrogen to unsaturated fats. This can convert liquid fats into solids and improve taste, texture and shelf-life.
What are some functions of proteins and what is the relationship between shape and function?
Proteins serve structural, protective, regulatory, contractile and transport functions.
A protein’s 3D shape determines its function. If a protein’s shape has been altered enough to destroy its function, it is said to be denatured. Very few proteins can be re-natured.
What are the two main types of nucleic acids and what makes up a nucleotide?
The two main types of nucleic acids are Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA).
A nucleotide consists of one sugar molecule, a phosphate group and a nitrogenous base (A+T or G+C)
What 6 traits do all cells have in common?
- A cell membrane
- DNA as blueprint for proteins and replication
- RNA for protein synthesis
- Ribosomes for protein manufacture
- Proteins that do the cell’s work
- Cytoplasm (jelly-like fluid inside cell)
Describe the phospholipid bilayer structure of the cell membrane.
A cell membrane is 2 phospholipid layers thick (hence bilayer). Each phospholipid layer consists of a phosphate group head (hydrophilic) and two fatty acid tails (hydrophobic). The heads form the internal and external boundaries of the cell membrane. The fatty acids are in-between these two boundaries.
Proteins and phospholipids move laterally within the bilayer, this is known as the fluid mosiac model.
Why are cells so small?
Cells need a large surface area relative to interior volume in order to efficiently exchange nutrients and waste. Since volume increases faster than surface area, if the cell gets too large the exchange rate will start to drop below the optimum level. Cells with organelles can grow larger due to division of labor.
What is the difference between prokaryotic and eukaryotic cells?
Prokaryotic cells are small and simple in structure. They do not have a nucleus and their DNA and organelles float freely within the cell. There are distinct spaces for performing tasks, but not separated by any barriers.
Eukaryotic cells are much larger (10x-100x) and complex in structure. They have a membrane-bound nucleus containing DNA. The membrane-bound organelles allow them to perform division of labor. Each organelle has its own environment optimized to its function.
Prokaryotic organisms are single cell only. Eukaryotic organisms can be both single or multi-cellular.
What are the basic functions of the following organelles: nucleus, chloroplasts, mitochondria?
Nucleus - Where DNA is stored, has all info needed for cell function
Chloroplasts - Captures radiant energy from the sun to produce food (does not produce energy!)
Mitochondria - Where cell energy is produced via cellular respiration. Not present in prokaryotes.
What is Endosymbiotic Theory?
The Endosymbiotic Theory suggests where mitochondria and chloroplasts came from. A long time ago, an eukaryote absorbed a prokaryote which was very good at converting food into energy. Over time, the genetic changes made each dependent on one another for survival. The prokaryote most likely evolved into an organelle. Evidence of this: mitochondria/chloroplasts are similar in size to prokaryotes, have their own DNA and reproduce by binary fission.
Describe the flow of energy through lifeforms
Lifeforms gain and lose energy through the making and breaking of chemical bonds. The chemical bonds in food are a source of potential energy. Energy that is used is lost as heat, it is not recycled (one-way).
Define endergonic and exergonic reactions
Endergonic reactions require (absorb) energy, allowing us to build more complex molecules from simpler ones. The reactants (small molecules) have less energy than the products (complex molecules). Photosynthesis is endergonic.
Exergonic reactions release energy, such as when complex molecules break apart. The products (small molecules) have less energy than the reactants (complex molecules). Cell respiration is exergonic.
What is ATP?
ATP (adenosine triphosphate) is a high energy molecule that can store energy and release it again and again like a rechargeable battery. It is made up of a sugar, nitrogenous base and 3 phosphate groups. ATP becomes ADP after energy release (lose a phosphate). ADP becomes ATP after phosphate added back in.
How is light absorbed and reflected by plants and why do leaves change color in the fall?
Light is absorbed or reflected by the pigments (chlorophyll a/b, cartenoid) in a leaf. Leaves change color in the fall because the amount of chlorophyll a and b is less than that of cartenoid which reflects red/orange light. The chlorophyll is being broken down and stored in the branches before the leaves fall off. If the plant loses too much chlorophyll it cannot survive!
