# Science Pre-IB

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1. What characteristics do all living things exhibit?
They are made of cells, cells contain DNA, DNA is to determine inheritance, All cells use energy, cells have metabolism, they respond to stimuli, they have homeostasis,
2. What are the steps of the scientific method
Observation of natural phenomena, Pattern recognition, Formation of a hypothesis, Controlled experimentation and making predictions to explain a natural event.
3. What is a scientific theory?
The best most current explanation we have to explain some natural phenomenon.
4. What is a controlled experiment?
An experiment in which you are comparing a two groups, one which is your control group, where you have not changed anything, and another group where you have changed one variable in the experiment deliberately, so you can attribute the differences in the data to an effect from the variable.
5. Compare the size of micrometers and millimeters.
A micrometer is one/thousandth of a millimeter.
6. How do you figure the total magnification of a microscope?
Magnification of the microscope = Magnification of the objective (the closest lens to the object) times the magnification of the eyepiece lens
7. What happens to the size of your field of view as magnification increases with a microscope?
You can see things more detailed. You may see a smaller piece of the subject but the less that you do see you see better and larger than you saw it before and you see more detail in what you are looking at.
Giga
billion
Mega
million
Kilo
thousand
Hecto
hundred
Deka
ten
Deci
tenth
Centi
hundredth
Milli
millionth
Micro
billionth
Nano
trillionth
Pico
9. Describe the structure of an atom.
An atom has a nucleus where you find protons and neutrons and shells of electrons that are very far away.
How do you determine the number of protons, neutrons, and electrons?
The number of protons matches the atomic number. The mass is the number of protons and neutrons added together. The electrons are of the same number as the protons. The neutrons can outnumber the protons.
10. What six elements make up 96% of all living matter?
Hydrogen, Oxygen, Carbon, Nitrogen, Phosphorus, Sulfur
11. What information does a chemical formula give you?
It tells you which elements are in the compound and the number of atoms of each element in the compound.
12. What elements are always present in organic compound?
Carbon and hydrogen and usually oxygen
13. What are the four classes of macromolecules?
Carbohydrate, Lipids, Proteins, Nucleic acids
What elements are found in Carbohydrates
- Carbon, Hydrogen, Oxygen (may have phosphate)
What elements are found in Lipids -
Carbon, Hydrogen, Oxygen
What elements are found in Proteins
Carbon, Hydrogen, Oxygen, Nitrogen
What elements are found in Nucleic Acids
â€“ Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus
What are the building blocks of Carbohydrates
-saccharides composed of 3-7 carbons
What are the building blocks of Lipids
fats, oils, waxes
What are the building blocks of Proteins
â€“ amino acids
What are the building blocks of Nucleic acids
â€“ purine or pyrimidine, ribose, phosphate
14. Name several carbohydrates.
monosaccharides, disaccharides, starch
Name some Monosaccharides:
, Fructose, Galactose, Glucose
Name some Disaccharides:
Sucrose (glucose + fructose) Lactose (glucose + galactose) Maltose (glucose + glucose)
15. What are the characteristics of enzymes?
They are proteins; they are not permanently used up in a reaction; they are specific in that their shape makes them bind to a particular substrate; they usually end in â€“ase and they are named for their substrate.
16. Describe the structure of a nucleotide.
DNA has a 5 carbon sugar, deoxyribose, , a nitrogen base of purine or pyrimidine which consist of Adenine, Guanine, Cytosine, and Thymine, and phosphate.
17. Who determined the structure of a DNA molecule?
Watson and Crick
18. What is activation energy?
The initial energy used to break a chemical bond and start a chemical reaction.
19. Why do the hydrogen atoms in a water molecule have a slightly positive charge?
Because their electrons are more attracted to the oxygen than the hydrogen.
20. What is ionization?
You loose an electron or gain an electron so that it has a positive or negative charge.
21. What do the numbers on the pH scale mean?
1-6 is acidic, 7 is neutral, and 8-14 is basic.
22. Who first described and named cells?
In the 1600s Aton van Leewenhoek described living cells as seen through a simple microscope. Robert Hooke named the cell in 1665. He observed the empty spaces in a piece of cork.
Who contributed ideas to the development of cell theory?
Aton van Leewenoek
Robert Hooke
Matthias Schleiden
Thomas Schwann
23. What is cell theory?
1. All organisms are composed of one of more cells.
2. The cell is the basic unit of structure of all organisms. 3. All cells come from existing cells.
4. They have a plasma membrane, cytosol, ribosomes, and genetic material
Aton van Leewenoek
â€“described living cells as seen through a microscope
Robert Hooke
named the cell, noticing empty space
Matthias Schleiden
Thomas Schwann
24. Compare and contrast prokaryotic and eukaryotic cells.
Eukaryotic:
1.Nucleus
2.Chromosomes in pairs
3.Cell division by mitosis
4. DNA bound to histones
5. Membrane enclosed organelles
6. Streaming in cytoplasm
7. Larger ribosomes
8. Complex cytoskeleton
9. Complex flagella
10. Cellulose in cell walls
What do you find in Prokaryotic
cells (to contrast with Eukaryotic):
1. No nucleus
2. Single chromosome
3. Cell division w/o mitosis
4. No histone proteins
5. No membrane enclosed organelles
6. No streaming in cytoplasm 7. Smaller ribosomes
8. Simple cytoskeleton
9. simple flagella
10. No cellulose
What is a eukaryote?
all organisms except viruses, bacteria and cyanobacteria
Define Ribosomes-
where amino acids are assembled to form proteins
Define Mitochondria-
power plant of the cell; cellular respiration (burning sugar molecules and making ATP)
Define Endoplasmic Reticulum
transports protein around the cell.
Vacuoles-
water storage area; dissolves minerals.
Golgi Apparatus-
packages, stores, and ships proteins
Lysosomes-
stomach of the cell; breaks down and recycles old organelles of the cell.
Chloroplasts-
take light energy and convert it to sugar to take and make energy out of.
Centrioles-
help the cell divide.
Cell membrane-
semi-permeable membrane that controls what enters and leaves the cell.
Nucleus â€“
control center of the cell
Chromosomes (DNA) â€“
passes on hereditary information and controls cell activity
Nuclear membrane â€“
protects DNA
Nucleolus â€“
makes ribosomes
Cytoplasm â€“
protects organelles
27. How do plant and animal cells differ?
Plant cells have cell walls and chloroplasts and a central vacuole. Animal cells have a pair of centrioles One has photosynthesis the other has cellular respiration
Marker proteins -
help to identify the cell's type and identity
Receptor proteins -
help to interact with specific molecules that convey signals into the cell
Channel proteins -
help substances move through the membrane either with or without a requirement for energy
30. Name two types of passive transport.
Diffusion, osmosis,facilitated diffusion
Diffusion -
when substances cross the membrane because they are either very small or hydrophobic, following concentration gradients
Osmosis -
when water crosses a membrane following its concentration gradient from a hypotonic side to a hypertonic side of a membrane
Facilitated diffusion -
movement through a passive channel which doesn't require energy but follows the concentration gradient.
31. Why are food webs used instead of food chains?
They reflect the complexity of relationships better.
32. Draw a food web that includes at least two of each of the following: producers, herbivores, carnivores, and decomposers.
Producers-
a plant that makes its own food by photosynthesis.
Herbivores-
they feed on plants.
Carnivores-
they consume other animals.
Decomposers
33. What is plankton?
Small (often microscopic) plants and animals floating, drifting or weakly swimming in bodies of fresh or salt water.
34. How many trophic levels are usually present in an ecosystem?
Usually they have about four layers.
35. What is biomass?
A quantitative estimate of the entire amount of living organisms in a particular habitat; it can be measured in terms of volume, mass, or caloric energy.
Population-
a group of organisms of one species that interbreed and live in the same place at the same time
Community-
a collection of interacting populations
Ecosystem-
made up of interactions among populations in a community.
Habitat â€“
the location where an organism lives
Niche â€“
the role an organism plays in its ecosystem
Endergonic reaction-
a chemical reaction that consumes energy.
Exergonice reaction-
a chemical reaction that releases energy in the form of heat, light, etc.
Oxidation-
Any reaction which removes electrons from a molecule or atom.
Reduction-
The gain of electrons by a molecule or ion.
Coenzyme-
An organic, nonprotein molecule that binds with an apoenzyme (a protein molecule) to form an active enzyme. Coenzymes are often derived from vitamins.
38. Why is ATP called the energy currency of the cell?
When ATP is split apart it releases energy that can be used for things to move across membranes or to fuel reactions. Each cell uses about 10 million ATP molecules per second.
39. What is a biochemical pathway?
An ordered series of enzyme-catalyzed reactions that forms a product.
40. What information can you learn from a karyotype?
aneuploidy, trisomy, monosomy
Aneuploidy â€“
the wrong number of chromosomes
Trisomy â€“
three copies of the same chromosome
Monosomy â€“
one copy of the same chromosome
Gamete-
Haploid cell that will combine with another gamete in sexual reproduction
Zygote-
The single cell formed by the union of a sperm and an ovum or other male and female gametes.
Diploid-
A full set of genetic material, consisting of paired chromosomes one chromosome from each parental set. Most animal cells except the gametes have a diploid set of chromosomes. The diploid human genome has 46 chromosomes.
Haploid-
A single set of chromosomes (half the full set of genetic material), present in the egg and sperm cells of animals and in the egg and pollen cells of plants. Human beings have 23 chromosomes in their reproductive cells.
Trisomy-
A cell or organism which has two full sets of chromosomes (is thus diploid), but has a third copy of one of its chromosomes.
Duplication-
In this situation, a DNA sequence is tandemly repeated because of a replication accident or unequal crossing over.
Translocation-
The movement or reciprocal exchange of large-chromosomal segments, typically between two different chromosomes.
Inversion â€“
occasionally a chromosome will break in two places and the piece which is broken rejoins UP SIDE DOWN.
Nondisjunction-
When sister chromatids do not come apart successfully; can lead to trisomy and monosomy
Binary fission -
the way that prokaryotic DNA duplicates through making an extra copy of the chromosome
42. What are the stages of the cell cycle?
G1, S, G2
What happens in G1?
ordinary cell life: making proteins; making new organelles; growing bigger
What happens in S phase?
synthesis duplicating DNA
What happens in G2?
making microtubules
43. What are the phases of mitosis?
Interphase, Prophase, Metaphase, Anaphase, Telephase, Cytokinesis
What happens during
What happens during Interphase?
duplication of DNA
What happens during Prophase?
forming spindle; chromosomes visible; nucleolus disappears; nuclear membrane disappears
What happens during Metaphase?
chromosome pairs line up at equator, attached to spindle fibres; short phase
What happens during Anaphase?
sister chromatids move apart from each other toward centrioles at opposite poles
What happens during Telophase?
cell begins to divide; chromosomes go back to strings; nucleus begins to form
What happens during Cytokinesis
cells break apart forming two daughter cells
44. What is crossing over? When does it occur?
The breaking during meiosis of one maternal and one paternal chromosome, the exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can result in an exchange of alleles between chromosomes.
45. What are the products of photosynthesis?
Products of photosynthesis: One molecule of glucose, six oxygens, six water molecules
What are the raw materials of photosynthesis?
Raw Materials of photosynthesis: Energy, six molecules of carbon dioxide, twelve molecules of water
46. What are the possible end products of fermentation?
Lactate, ethanol, carbon dioxide
47. What occurs during the light reactions of photosynthesis?
Light â€“ water is taken in and O2 is formed as a product with ATP and NADPH
What occurs during the dark reactions?
Dark â€“ Carbon dioxide is taken in and sugar is made and NADP AND ADP and Pi
48. Explain the process of cellular respiration.
An animal uses glucose, oxygen and water to make carbon dioxide, water and energy.
49. What is the function of chlorophyll?
Its green pigment is used to capture light energy during photosynthesis from inside thylakoids.
50. Explain feedback inhibition of cellular respiration.
The ratio of ATP to ADP and AMP reflects the energy status of the cell. Citrate and ATP inhibit phosphofructokinase, so when their concentration rise, the enzyme slows glycolysis. As the rate of glycolysis slows, the Krebs cycle also slows. ADP and AMP, in contrast, turn on phosphofructokinase, so when their concentrations relative to ATP rise, the enzyme speeds up glycolysis, which speeds of the Krebs cycle.

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