IB Biology Exam Review Part II

What is mitosis?

The division of the nucleus into two genetically identical daughter nuclei

What is interphase?

The period before mitosis

What happens to DNA in interphase?

The replication of DNA. Each chromosome is converted from a single DNA molecule into two identical DNA molecules.

What are two identical DNA molecules called?

Chromatids

What are the events and phases of mitosis?

Prophase, metaphase, anaphase, and telophase.

When does many metabolic reactions occur in the life of a cell?

During interphase

What happens to mitochondria and cytoplasm in interphase?

The numbers of mitochondria and cytoplasm increase

What are the phases of interphase?

G₁ phase, S phase and G₂ phase

What happens in the S phase of interphase?

The cell replicates all the genetic material in its nucleus

Why is there a G₀?

It is where genes that are never going to divide go

What happens during prophase?

Supercooling, breaking down of nucleolus, microtubules grow from microtubule organizing centers to form a spindle shaped array that links poles of cell, nuclear membrane breaks down.

What happens during metaphase?

Microtubules grow and connect to each centromere on chromosomes, microtubules put under tension to test attatchment.

What happens during anaphase?

Each centromere divides which separates each chromatid as the spindle microtubules pulls them to the poles of the cell, mitosis creates genetically identical nuclei.

What happens during telophase?

Chromatids reach poles and become called chromosomes, chromosomes pulled into tight groups around microtubule organizing center and nuclear membrane reforms, chromosomes uncoil and nucleolus formed.

How does cytokinesis occur in animals?

Plasma membrane pulled to equator to form cleavage furrow using actin and myosin protein in cell, when cleavage furrow reaches center, cell is pinched into two cells.

How does cytokinesis occur in plants?

Vesicles move to equator to form tubular structures across it, these tubular structures merge to create two layers of membrane across equator (develops into plasma membrane of daughter cells and connects to existing plasma membranes at side of cell).

Pectins and other substances brought in vesicles and deposited by exocytosis between two new membranes formed middle lamella which will link new cell walls. Daughter cells bring cellulose and deposit at equator adjacent to middle lamella creating cell walls.

What are the purpose of cyclins?

They are proteins that makes sure cell tasks are performed correctly.

What do cyclins do?

They bind to enzymes called cyclin-dependent kinases and connects phosphate groups to proteins making them active

Who discovered cyclins?

Tim Hunt

What are carcinogens?

Chemicals and agents that cause cancer

What are oncogenes?

Genes that become cancer causing after mutation

What is metastasis?

The movement of cells from primary tumors to create secondary tumors.

Wha this meiosis?

the division of a cell which produces gametes and un identical cells.

At the beginning of meiosis, how many cells are there?

There is one diploid cell

How many phases of meiosis are there?

Two phases

After meiosis I, how many cells are there?

Two haploid cells

After meiosis II, how many cells are there?

Four haploid cells

What does sexual life cycles bring?

They bring genetically diverse cells

What happens in meiosis I?

Homologous chromosomes pair up with each other in a process called synapsis, crossing over takes place with junctions of each chromatid being crossed over to the other, spindle microtubules form at the poles of the cell, the spindle microtubules attach to the centromeres of the chromosomes and pull away as it would in mitosis making disjunction occur.

What determines the attachment of chromosomes in each bivalent?

The way in which the pair of chromosome is facing (orientation)

What holds together the two chromosomes in each bivalent?

Chiasmata

What is amniocentesis?

Putting a needle through abdomen wall to withdraw a sample of amniotic fluid from amniotic sac in order to obtain cells from a fetus.

What is chorionic villus sampling?

Putting a tool through the vagina to get cells from chorion

What is non-disjunction?

When homologous chromosomes don’t separate correctly

In meiosis I, how are the chromosomes and chromatids separated?

The chromatids stay together, and the two chromosomes are pulled apart in the first phase. This is due to the replication of DNA before hand.

What are the phases of meiosis I and II?

Prophase I, Metaphase I, Anaphase I, and Telophase I

Prophase II, Metaphase II, Anaphase II, and Telophase II

How many covalent bonds can carbon atoms form with other atoms?

4

What are the four carbon compounds?

Carbohydrates, lipids, proteins, and nucleic acids

What makes a carbohydrate one?

They are composed of carbon, hydrogen, and oxygen. There is a ratio of two hydrogen atoms to one oxygen.

What makes a lipid one?

They are insoluble in water. Triglycerides are fats if they are solid at room temperature or oils if they are liquid at room temperature.

What makes proteins one?

They are composed of one or more amino acids. The amino acids contain carbon, hydrogen, oxygen, and nitrogen. Two of the amino acids contain sulphur.

What makes nucleic acids one?

They have chains of subunits called nucleotides which contain carbon, hydrogen, oxygen, nitrogen, and phosphorus.

What is the formula for ribose?

C₅H₁₀O₅

What is the formula for glucose?

C₆H₁₂O₆

What makes up amino acids?

An amine group, a carboxyl group, a hydrogen atom, the R group

How do you tell the carbon compounds apart?

Proteins: have C, H, O, and N whereas carbohydrates and lips contain no N. Many proteins also contain Sulphur.

Carbohydrates: contain H and O in a ratio of 2:1

Lipids: Contains relatively less oxygen than carbohydrates

What is metabolism?

The sum of all reactions that occur in an organism

What is anabolism?

The synthesis of complex molecule from simpler molecules including the formation of macromolecules from monomers by condensation reactions

What is catabolism?

The breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.

What does it mean to be aerobic?

Organisms, cells, processes and life which requires oxygen, giving yield of ATP from glucose

What does it mean to be anaerobic?

The unique capability of organisms, cells, processes and life to continue even in the absence of molecular oxygen.

What is ADP?

What builds ATP from a link with a phosphate group

What is ATP?

A chemical substance that controls and releases energy (a source of energy)

What is ethanol?

A component which glucose breaks down into in yeast and plants

What is glucose?

A component of sugar that is broken down during anaerobic respiration.

What are organic compounds?

The things obtained through food in plants and animals

What is the point of cell respiration?

To control the release of energy from organic compounds to produce ATP which can be used in a cell. This can be done by breaking down inorganic compounds.

What are humans’ source of organic compounds?

The foods consumed such as carbohydrates and lipids, sometimes amino acids from proteins.

What are plants source of organic compounds?

They use carbohydrates or lipids previously made by photosynthesis as their source.

Compare the structure of ADP and ATP

ATP is obtained through the energy of food and is readily available to be used. ATP is also used as energy for cellular work and is released by splitting into ADP and phosphate.

ADP is less readily available than ATP. ADP and phosphate can be converted to ATP by cell respiration.

What main types of energy-requiring activities do cells perform?

1. Synthesizing large molecules like DNA, RNA and proteins
2. Pumping molecules or ions across membranes by active transport
3. Moving things in a cell

What is the anaerobic cell respiration of animals?

Glucose is broken down to lactate by ADP turning to ATP

What is the anaerobic cell respiration of yeast and plants?

Glucose is turned into ethanol and carbon dioxide by ADP turning to ATP.

How doe humans use yeast?

1. Kneading and creating bubbles in bread
2. Converts sugar into ethanol (bioethanol is used as fuel)
3. Producing bioethanol

What is chlorophyll’s role in photosynthesis?

To absorb red and blue light and reflect green light

What is the role of carotene in photosynthesis?

It absorbs essential pigments of light

What is an absorption spectrum?

A graph showing the percentage of light being absorbed at each wavelength by a pigment or group of pigments

What is an action potential?

A graph showing the rate of photosynthesis at each wavelength of light

What is photolysis of water?

The splitting of water to release electrons that are needed elsewhere.

What are the limiting factors of photosynthesis?

Temperature, light intensity, and carbon dioxide concentration

What are the wavelengths of the different types of light?

Blue: 450 - 500 nm

Green: 525 - 575 nm

Red: 650 - 700 nm

Which wavelength has more energy?

Shorter wavelengths

What is the activation energy?

Energy that is put into reaching the transition state and is used to break or weaken bonds in the substrates of enzymes. It is reduced when binding occurs.

What are the different types of inhibitors?

Competitive and non-competitive

What are inhibitors?

Chemical substances that bind to enzymes and reduce the activity of the enzyme.

What do competitive inhibitors do?

They interfere with the active site so that the substrate cannot bind

What do non-competitive inhibitors do?

They bind at a location other than other than the active site and denatures the enzyme therefore the substrate cannot bind to the active site.

What happens to the rate of the enzyme activity when there is a competitive enzyme present?

When the concentration of the substrate exceeds the amount of the inhibitor, the maximum rate of the uninhibited enzyme can be reached

What happens to the enzyme activity when there is a non-competitive enzyme present?

The maximum I’m rate cannot be reached because the non-competitive inhibitor limits the access of substrates to the enzyme.

What are allosteric interactions?

When chemical substances bind to special site on the enzyme away from the active site.

Where do chemical substances bind to on an enzyme?

The allosteric site

What is chemogenomics?

Research into metabolic pathways

What is oxidation?

The loss of electrons

What is NAD?

The main carrier of electrons in respiration

How does NAD accept two electrons?

Two hydrogen atoms are removed from the substance that is being reduced or one of the hydrogen atoms is split into a proton and an electron.

How is oxygen related to oxidation and reduction?

With added oxygen, there is oxidation because the oxygen has a high affinity for electrons and therefore drives electrons away.

With loss of oxygen, there is reduction.

What is phosphorylation?

The addition of a phosphate molecule to an organic molecule.

What does exergonic reaction mean?

That the hydrolysis of ATP is releasing energy tot he environment

What does glycolysis do?

It gives a small net gain of ATP without the use of oxygen

What is pyruvate?

The product of glycolysis turning glucose.

What is decarboxylations?

The removal of carbon and oxygen.

What happens to pyruvate in the link reaction?

It gets converted into acetyle coenzyme A. This happens because the pyruvate is decarboxylated and oxidized to form an acetyle group.

What is the Krebs cycle?

Two decarboxylations and four oxidations. Most of the energy released in oxidation’s is the link reaction and the Krebs cycle which is used to reduce hydrogen carriers.

What is oxidative phosphorylation?

The final part of aerobic respiration because ADP is phosphorylated to produce ATP using the energy released by oxidation.

What happens in the electron transport chain?

Reduced NAD and FADH₂ donate their electrons to electron carriers and they are passed from carrier to carrier, utilizing the energy to transfer protons across the inner membrane from the matrix into the inter membrane space.

What is chemiosmosis?

The release of energy by oxidation to ATP production

What is the mitochondrion?

The site of aerobic respiration.

Where is the thylakoid space?

In the thylakoid membrane which is the interconnected membranes of the inner membrane of a plant. Which is where light-dependent reactions occur.

What does light-dependent reactions produce?

Reduced NADP and ATP are produced in these reactions.

Where are light-independent reactions taking place?

In the stroma which is a thick protein-rich medium which has enzymes for the use in the light-independent reactions (Calvin cycle).