2pt q's

Question 1

What is homeostasis. Give an example.

Answer 1

Homeostasis is the ability to sense and react to stimuli in order to maintain a constant internal environment when the external environment changes. Ex: Dilation of capillaries to release heat in response to high temps in the environment.

Question 2

Describe the flow of energy and cycling of materials through the ecosystem

Answer 2

Producers make their own food by extracting energy and nutrients from non-living sources (sun/water/co2). Consumers obtain energy and nutrients by eating other organisms. Decomposers obtain energy and nutrients from wastes or dead organisms and recycle

Question 3

List the two parts of the scientific name and define them

Answer 3

Genus/Species Genus is a group of species that share unique features. Species is a distinct type of organism that share one or more heritable traits and can interbreed with each other.

Question 4

List the factors that contribute to water’s life giving properties

Answer 4

Water is cohesive and adhesive, it regulates temperature, expands when frozen, participates in chemical processes, and it is a solvent.

Question 5

How is a peptide bond formed?

Answer 5

A peptide bond is formed by the dehydration synthesis of amino acid monomers. (bonds between carboxal and hydroxal groups)

Question 6

State the cell theory 3/3

Answer 6

Early: Organisms made of one or more cells, Cell is the fundamental unit of life, Cells come from preexisting cells. Additional: All cells have same basic chemical composition, All cells use energy, All cells contain DNA that is duplicated and passed on as the cell divides

Question 7

What is the difference between a nucleus and nucleoid?

Answer 7

A nucleoid is an irregularly shaped region of the cytoplasm that contains a single, circular DNA (found in prokaryotic cells). A nucleus is a membrane bound sac that houses DNA, found in eukaryotic cells.

Question 8

Define endergonic and exergonic reactions

Answer 8

An endergonic reaction results in a net gain of energy - the reactants have less potential energy than the product. An exergonic reaction results in a net loss of energy - the product has less potential energy than the reactants.

Question 9

Define oxidation reduction reactions

Answer 9

Redox reactions link an exergonic process with and endergonic one. An electron donor would undergo an oxidation reaction, losing energy because this is an exergonic reaction. The molecule simultaneously gaining this electron would be reduced in an endergonic reaction. The electron transferring reactions play a vital role in photosynthesis and cellular resp.

Question 10

Define passive transport and list the three different kinds of passive transport

Answer 10

Transport by which ions or molecules move along a concentration gradient (from high concentration to low concentration/does not require energy). Simple diffusion, facilitated diffusion, osmosis (water moves down its own gradient.)

Question 11

What are enzymes? List the factors that contribute to the enzyme substrate specificity?

Answer 11

Biological catalysts that increase the rate of chemical reactions. They are not consumed in the process, and they lower the activation energy. Complementary shape, charge, and hydrophobic/hydrophilic factors contribute to enzyme specificity.

Question 12

Define aerobic cellular respiration and write the chemical equation

Answer 12

C6-H12-O6 + (6)O2 ——–> (6)CO2 + (6)H2O + 36ATP A form of cellular respiration that requires oxygen in order to break down organic molecules for the production of ATP.

Question 13

List and define 2 methods by which ATP is made in the cell

Answer 13

Substrate level phosphorylation - An enzyme directly transfers a phosphate from a high energy donor to an ADP creating ATP (i.e. glycolysis). Chemiosmotic phosphorylation uses ATP synthase and the potential energy of a proton gradient to make ATP. As the gradient dissipates ATP synthase harnesses the energy into a usable form. (ATP)

Question 14

State where chlorophyll is located in a chloroplast and the function of chlorophyll in photosynthesis

Answer 14

Chlorophyll is located in photosystems embedded in thylakoid membranes. Hundreds of chlorophyll are found in antennae pigments which surround 2 modified chlorophyll in the reaction center. Antennae pigments gather light energy and pass it to the reaction center where it is transferred to electrons.

Question 15

What is water’s role in light reactions?

Answer 15

Electrons are replaced in photosystem II by hydrolysis. A molecule of water is split into 1/2 O2, 2H+ and 2 electrons. The 1/2 O2 is doubled and either released to the environment or used in respiration. The H+ remains in the thylakoid space.

Question 16

Briefly describe how C4 and CAM plants differ in carbon fixation reactions.

Answer 16

In the C4 pathway, CO2 combines with 3C molecule to form 4C oxaloacetate which is usually reduced to a malate. Malate moves into adjacent bundle sheath cells where the CB cycle fixes the carbon a second time. Crassualacean acid metabolism uses temporal separation. Stomata open at night, mesophyll cells incorporate CO2 into malate and store it in vacuoles. During the day, malate is moved into chloroplasts, release CO and it is fixed in CB cycle.

Question 17

What is glysolysis/Where does glycolysis happen in the cell/What is the net yeild of ATP and NADH at the end of glycolysis

Answer 17

Glycolysis is a universal reaction that splits glucose into (2) 3C pyruvate. Glycolysis requires energy to start and yeilds a net of 2 ATP and 2 NADH. Glycolysis occurs in the cytoplasm.

Question 18

Describe the differences between lactic acid fermentation and ethanol fermentation

Answer 18

Ethanol fermentation produces CO2 and requires an intermediate (pyruvate–>aceltylaldehyde–>ethanol). Lactic acid fermentation does not produce CO2 and does not use an intermediate (pyruvate–>lactate).

Question 19

List the three stages of aerobic cellular respiration and where in the cell the stages occur

Answer 19

Glycolysis/Kreb’s cycle/Electron transfer phosphorylation cytoplasm/mitochondrial matrix/inner membrane of mitochondria

Question 20

Define photorespiration

Answer 20

The process by which in the presence of light plant consumes oxygen and releases carbon dioxide (instead of fixing carbon dioxide) during photosynthesis.

Question 21

List the two stages of photosynthesis and state where in the chloroplast of the plant cell does each stage occur?

Answer 21

Light dependent reactions happen in the thylakoid membranes. Light independent reactions happen in the stroma.

Question 22

What are the 3 types of RNA and how does each contribute to protein synthesis?

Answer 22

mRNA carries the genetic code information from DNA. tRNA is a “connector” that connects the information in mRNA to an amino acid. rRNA is the main component of ribosomes that assembles the polypeptides and also catalyzes bonds.

Question 23

Describe the functional differences in RNA and DNA

Answer 23

DNA: stores RNA and protein encoding information, transfers information to next generation of cells. RNA: carries protein-encoding information, acts as a connector to amino acids, helps to make proteins, catalyzes some reactions.

Question 24

Describe the structural differences in RNA and DNA

Answer 24

Single vs. double strand, Uracil instead of Thymine, Ribose vs. Deoxyribose, RNA smaller than DNA.

Question 25

State Chargaff’s rule

Answer 25

1. The amounts of thymine and adenine in DNA are the same and the amounts of cytosine and guanin are the same (A=T, G=C). 2. The proportion of adenine and guanine differs among species.

Question 26

Where are anticodons and codons located? List the start and stop codons. Which amino does the start codon code for.

Answer 26

Codons are located in mRNA, anticodons in tRNA. AUG - methionine, UAA, UAG, UGA

Question 27

How is mRNA modified after transcription? (post transcriptional modification)

Answer 27

mRNA is modified before leaving the nucleus. On the 5’ end a modified guanine cap is added which helps ribosomes attach. On the 3’ end adenines are added forming a poly A tail which determines the longevity of the mRNA. Introns are removed and exons spliced together.

Question 28

State the function of mitosis in multicelled eukaryotes and in single celled organisms

Answer 28

In single celled organisms, mitosis is the basis for asexual reproduction. In multicelled organisms mitosis is used for growth and development and to repair and replace damaged tissue.

Question 29

What are the 4 major checkpoints in the eukaryotic cell cycle?

Answer 29

G1 - checks for damaged DNA, S - Checks that DNA is replicating properly, G2 - checks if all the DNA has replicated and that spindle machinery is in place, Metaphase - checks if the chromosomes are aligned properly and if the spindle fibers are connected to chromosomes properly (at kinetochores).

Question 30

Compare sexual reproduction and asexual reproduction

Answer 30

Asexual: Form of reproduction in which offspring arise from only one parent, by mitosis. Sexual: The combination of genetic material from 2 individuals to create a third. Meiosis/haploid/fertilization/diploid

Question 31

Compare haploid and diploid cells

Answer 31

Diploid cells have 2 sets of chromosomes, one from each parent and are noted as 2n. Haploid cells have 1 set of chromosomes and are noted as n. Fertilization and mitosis create diploid cells, meiosis creates haploid cells.

Question 32

Explain Aneuploidy/Polyploidy

Answer 32

Aneuploidy is any deviation from the exact multiple of the haploid number of chromosomes. Most aneuploids arise by nondisjunction and chromosomes may be present in multiple copies (trisomy) or one of a homolous pair may be missing (monosomy). Polyploidy is an organism or cell having more than twice the haploid number of chromosomes and is the result of total nondisjunction during mitosis or meiosis.

Question 33

Define genotype and phenotype

Answer 33

A genotype is the combination of alleles for a particular gene. A phenotype is an observable characteristic of an organism.

Question 34

Mendel’s law of segregation and Law of independent assortment

Answer 34

Segregation: The two alleles of each gene are packaged into separate gametes; they segregate from each other during gamete formation. Ind Asst.: The segregation of the alleles for one gene does not influence the alleles for another gene. Alleles for 2 different gene are randomly packed in respect to each other.

Question 35

P, F1 and F2 generations

Answer 35

P is the parental or starting generation. F1 and F2 (filial) indicate the generation of offspring (1st and 2nd respectively)

Question 36

What is a test cross?

Answer 36

A test cross is a mating of an individual of an unknown genotype for a trait with an individual that is homozygous recessive for that same trait. The phenotypic ration of the offspring can be used to determine the genotype of the unknown individual.

Question 37

Explain epistasis and Pleiotropy

Answer 37

Epistasis: One gene masksor affects another gene’s expression (i.e. baldness hides the effects of a widow’s peak) Pleiotropy: One gene has multiple effects on the phenotype. (i.e. one protein is used in many parts of the body. Marfan)

Question 38

How are dideoxynucleotides different from regular nucleotides

Answer 38

Dideoxynucleotides are lacking a 3’ hydroxal group found in deoxynucleotides. Thus, they can’t form a 3’-5’ phosphodiester bond required in chain elongation and the sequence is teminated when a dideoxynucleotide is encountered. They are also fluorescently tagged.

Question 39

Define restriction enzymes with one example

Answer 39

An enzyme having the property of cleaving DNA molecules at or near a specific sequence of bases. Used for gene splicing, example: Eco RI

Question 40

Define an STR and how is it used in DNA profiling

Answer 40

A short tandem repeat is 2-5 nucleotides long, they repeat one after another, can be up to 50 repeats long, and are found in non-coding regions of DNA. Individuals have different numbers of these repeats so they can be used as a unique identifier. DNA is amplified w/ PCR and 13 repeats are marked with fluorescent tags. Electrophoresis and fluorescent imaging are used to create a unique profile. (court cases, forensics)

Question 41

Compare and contrast stem cells and differentiated cells/list define the 2 categories of animal stem cells

Answer 41

Stem cells are undifferentiated and can specialize to become any type of body cell. Differentiation is the process by which less specialized cells become more specialized. Differentiated cells are cells that have specialized to have a specific function. Embyonic/totipotent/embryos/all types
Adult/pluripotent/various parts/limited subset

Question 42

Define microevolution and macroevolution

Answer 42

Small scale evolution - realatively short term changes in the allele frequency from generation to generation. Large scale evolutionary change - the descent of different species from a common ancestor over many generations/long periods of time.

Question 43

State the theory of evolution by natural selection

Answer 43

All species present on Earth today are descendants of a single common ancestor, and all species represent the product of millions of years of accumulated micro evolutionary changes.

Question 44

Define natural selection

Answer 44

Natural selection is the differential survival and reproduction of individuals of a population that vary in the details of their shared, inherited traits.

Question 45

Briefly explain the mechanisms of evolution

Answer 45

Genetic drift - Change in allele frequencies that occurs purely by chance (stepped on beetles) Migration - A group of a species joins another group increasing the frequency of the alleles that it carries in the population. Mutation - Change in a DNA seq Natural Selection - differential survival and reproduction of ind of a pop that vary in the details of their shared inherited traits.

Question 46

Describe the endomembrane system. (4)

Answer 46

The endomembrane system is a series of interacting organelles between the nucleus and cell membrane of a eukaryotic cell that exchanges materials in transport vesicles. It makes/modifies/transports proteins and lipids for secretion or insertion into the cell membrane. It also destroys toxins and recycles wastes. It includes: nuclear envelope, ER, GA, lysosomes, vacuoles and cell membrane.

Question 47

What contributes to genetic variability?

Answer 47

In crossing over, homologous chromosomes align and swap segments with each other which results on the chromosomes having new allele combinations. Crossing over occurs at random, so the gametes produced in one round of meiosis are not identical in the subsequent round. In independent assortment, homologous chromosomes can be attached to either spindle pole in metaphase 1, so each homologue can be packaged into either one of two nuclei. In fertilization, chance combinations of maternal and paternal chromosomes combine to produce a unique combination of genetic information.

Question 48

Describe the cell cycle

Answer 48

The cell cycle consists of three phases that occur from the point of the cell’s emergence until the cell divides into daughter cells. During interphase, the cell is not dividing, but protein synthesis, DNA replication, and other basic functions are occurring. Following interphase is mitosis during which the replicated genetic material divides. Finally, in cytokinesis, the cytoplasm divides and the cell separates. After cytokinesis, the daughter cells enter interphase and the cell cycle begins again.

Question 49

Ionic bond

Answer 49

An ionic bond is an attraction between oppositely charged ions. It is a strong bond, but broken easily. (NaCl)

Question 50

Covalent bond

Answer 50

A covalent bond is a strong, chemical bond in which two atoms share electrons. Depending on the electronegativity of the atoms, the bond will be polar or nonpolar covalent. (H2O)

Question 51

Hydrogen bond

Answer 51

A hydrogen bond is a weak attraction between a highly electronegative atom and a hydrogen atom participating in a separate polar covalent bond. It is not a chemical bond, and is easily broken. (Water to water)

Question 52

What is ER, two types

Answer 52

ER is an extension of the nuclear envelope that is folded into 2 types of membranes - smooth and rough. Rough ER is studded with ribosomes and functions in protein synthesis. Pro folded into tertiary form here. Smooth ERnis lacking ribosomes and synthesizes lipids, removes toxins and recycles wastes.

Question 53

3 types of respiration

Answer 53

The 3 types of respiration are anaerobic, aerobic and fermentation. Aerobic respiration is the complete oxidation of glucose to CO2 in the presence of oxygen (glycolysis-krebs-electron transport phosphorylation) producing 36-38 ATP. Anaerobic respiration is essentially the same as aerobic respiration, except the final electron acceptor is not oxygen and the byproduct not CO2. It produces 18 ATP. In fermentation, electrons from NADH reduce pyruvate and regenerate NAD+. Lactic acid and alcholic fermentation produce 2 ATP.

Question 54

Protein structure

Answer 54

Peptide chains fold into unique, 3D forms depending on the order and kinds of amino acids. The primary structure is a polypeptide chain with bonded carboxyl and hydroxal groups. The secondary structure forms coils, loops and sheets as the result of hydrogen bonds between parts of the polypeptide. The tertiary structure gives the polypeptide its overall shape (from H, ionic and covalent bonds forming.) The quarternary structure is the shape arising from interactions between multiple polypeptide units.

Question 55

Transcription

Answer 55

In the Initiation phase, enzymes unzip the DNA double helix exposing the template strand. RNA polymerase then attaches to a promoter (a DNA sequence that signals the gene’s start.) In elongation, RNA polymerase moves over the gene in a 3’ to 5’ direction, unwinds the DNA helix, reads the base sequence, and joins free RNA nucleotides into a complementary strand of mRNA. In termination, a terminator sequence signals the end of the gene, and the RNA, DNA and RNA polymerase separate. DNA becomes a double helix again. A RNA copy of a gene has been produced.

Question 56

Krebs

Answer 56

In Acetyl CoA formation, 2 pyruvate are broken down into 2 Acetyl CoA, 2 CO2 and 2 NADH. Acetyl CoA enters the krebs cycle and is added to oxaloacetate to form citrate. Several intermediates rearrange and oxidize citrate eventually turning it back into oxaloacetate and produce 2 ATP, 4 CO2, 2 FADH2, and 6 NADH. CO2 is released from the cell, and NADH and FADH2 are passed to the electron transport chain. The second stage takes place in the mitochondria matrix.

Question 57

LIDR

Answer 57

Carbon/light independent reactions take place in the stroma and synthesize CO2 into organic molecules. Catalyzed by ribulose biphosphate carboxylase/oxygenase (rubisco), 2 CO2 are added to 2 ribulose biphosphate (RuBP) to form an unstable intermediate. The intermediate splits into (12) 3C phosphoglycerate (PGA). Using the electrons and H+ from NADPH (12 NADPH–>12 NADH), PGA is transformed into (12) 3C phosphoglyceraldehyde (PGAL). 2 PGAL are used to make one glucose. 10 PGAL are used in RuBP regeneration - powered by ATP (6 ATP –> 6 ADP), PGAL is rearranged into 5 RuBP. RuBP can then be re-used.

Question 58

LDR

Answer 58

PSII - pigments collect and trans energy. Electrons are replaced by. ETCI pumps in H+. Gradient creates ATP. PSI repleneshes E. ETCII reduces NADP+ to NADPH to stroma.