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biology > Essay P3 Topics > Flashcards

Essay P3 Topics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Mitosis (5)

A

1) Interphase:
- DNA replicates by Semi-conservative replication.

2) Prophase:
- Nuclear membrane begins to breakdown.
- Centrioles move to poles of the cell.
- Chromatin supercoils and condense into chromosomes.

3) Metaphase:
- Spindle fibres form.
- Spindle fibres attach to the centromere of chromosomes.
- Chromosomes align at the equator

4) Anaphase:
- Spindle fibres shorten.
- Centromere splits.
- Sister chromatids are separated.
- Chromatids are pulled to opposite poles of the cell.

5) Telophase:
- Nuclear membrane begins to reform.
- Chromosomes unwind.

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2
Q

Meiosis (5)

A
  • Homologous chromosomes pair up
  • Maternal and paternal chromosomes are arranged in any order
  • Independent segregation
  • Crossing over, Bivalent, Chaismata
  • Equal proportions of chromatids are swapped between chromosomes
  • Produces new combinations of alleles
  • Chromatids separated at meiosis II/later
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3
Q

Phagocytosis (5)

A
  • Pathogen is engulfed by the phagocyte
  • Engulfed pathogen enters the cytoplasm of the phagocyte in a vesicle
  • Lysosomes fuse with vesicle, releasing hydrolytic enzymes
  • Lysosome enzymes break down the pathogen
  • Waste materials are ejected from the cell by exocytosis
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4
Q

Vaccines (5)

A
  • Vaccine contains antigen from pathogen
  • Macrophage presents antigen on its surface
  • T (helper) cell with complementary receptor protein binds to antigen
  • T cell stimulates B cell
  • With complementary antibody on its surface
  • B cell divides to form clone secreting / producing same antibody
  • B cell secretes large amounts of antibody
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5
Q

Starch digestion (5)

A
  • Salivary/pancreatic amylase
  • Starch -> Maltose
  • Maltose -> Glucose
  • Maltase
  • Hydrolysis
  • Glycosidic bonds
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6
Q

Protein digestion (5)

A
  • Hydrolysis of peptide bonds
  • Endopeptidases act in the middle of the polypeptide chain / produces shorter polypeptides / increases number of ends
  • Exopeptidases act at the end of the polypeptide chain
  • Dipeptidases act between two amino acids
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7
Q

Co-Transport (5)

A
  • Facilitated diffusion of amino acid (into cell when higher concentration in lumen)
  • Co-transport
  • Sodium ions actively transported from cell to blood/capillary
  • Creating sodium ion concentration gradient
  • Facilitated diffusion of amino acid into blood/capillary
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8
Q

Lipid absorption (5)

A
  • Micelles include bile salts and fatty acids
  • Micelles make the fatty acids more soluble in water
  • Bring fatty acids to the cells lining the ileum
  • Maintain higher concentration of fatty acids to cells lining the ileum
  • Fatty acids absorbed by diffusion
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9
Q

Transpiration (5)

A
  • Evaporation/transpiration from leaves
  • Creates cohesion/H-bonding between water molecules
  • Adhesion / water molecules bind to xylem
  • Creates continuous column of water
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10
Q

Translocation / transport of carbohydrates (5)

A
  1. Sucrose actively transported into phloem (cell); OR Sucrose is co-transported/moved with H+ into phloem (cell);
  2. (By) companion/transfer cells;
  3. Lowers water potential (in phloem) and water enters (from xylem) by osmosis;
  4. ((Produces) high(er) (hydrostatic) pressure; OR (Produces hydrostatic) pressure gradient;
  5. Mass flow to respiring cells OR Mass flow to storage tissue/organ;
  6. Unloaded/removed (from phloem) by active transport;
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11
Q

Transcription (5)

A
  • Hydrogen bonds break
  • Only one DNA strand acts as a template
  • Free RNA nucleotides align by complementary base pairing
  • In RNA, Uracil base pairs with Adenine on DNA
  • RNA polymerase joins adjacent nucleotides
  • By phosphodiester bonds
  • Pre-mRNA is spliced / introns are removed to form mRNA
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12
Q

Translation (5)

A
  • mRNA attaches to ribosome
  • tRNA anticodons bind to complementary mRNA codons
  • tRNA brings a specific amino acid
  • Amino acids join by peptide bonds
  • Amino acids join with the use of ATP
  • tRNA is released after amino acid is joined to polypeptide
  • The ribosome moves along the mRNA to form the polypeptide
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13
Q

Light Dependent Reaction (5)

A
  • Chlorophyll absorbs light energy + excites electrons
  • electrons removed (oxidation of chlorophyll) via photoionisation
  • electrons move along carriers/ETC releasing energy (by a series of REDOX reactions)
  • Energy released by electrons used to form proton gradient
  • H+ ions move through ATP synthase
  • providing energy to join ADP and Pi to from ATP
  • Photolysis of water produces 2 protons, 2 electrons and 1/2 oxygen
  • NADP reduced by electrons and protons / hydrogen
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14
Q

Light Independent Reaction / Calvin cycle (5)

A
  • Carbon dioxide combines with RuBP
  • Produces two GP molecules using enzyme Rubisco
  • GP reduced to triose phosphate
  • Using reduced NADP
  • Using energy from ATP
  • Triose phosphate converted to useful organic substances (glucose, amino acids etc.)
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15
Q

Glycolysis (5)

A
  • Phosphorylation of glucose using ATP
  • Phosphorylated glucose is unstable, so splits into 2 triose phosphate molecules
  • Oxidation of triose phosphate to pyruvate
  • Net gain of ATP
  • NAD reduced
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16
Q

Link / Krebs / ETC - Mitochondrion (5)

A

LINK:
- Occurs in the mitochondrial matrix
- Pyruvate oxidised and decarboxylated into acetate
- Produces reduced NAD and CO2
- Acetate combines with coenzyme A to produce Acetyl coA

KREBS + ETC:
- substrate level production of ATP / in KC
- production of reduced NAD / FAD
- electrons fed into ETC / used in oxidative phosphorylation
- electrons pass along carries / through ETC / through series of REDOX reactions
- Energy released
- Protons move into intermembrane space through ATP synthase
- ADP + Pi -> ATP

17
Q

Effect of IAA on root and shoot growth (5)

A

SHOOTS:
- IAA is synthesised in shoot tips
- IAA diffuses into growing region
- Light causes movement of IAA from light side to shaded side
- Proportionally more IAA on shaded side
- Stimulates cell elongation
- Causes directional growth as there is greater cell elongation on shaded side
- Shaded side grows faster and causes shoot to bend towards the light

ROOTS:
- IAA is synthesised in root tips
- IAA diffuses into growing region
- IAA moves towards shaded side
- Inhibits cell elongation
- Uneven growth (more cell elongation on side with less IAA)
- Causes directional growth away from light and towards gravity

18
Q

Sequence of events leading to release of NT and its binding to post synaptic neurone / synaptic transmission (5)

A
  • Depolarisation of presynaptic membrane
  • Ca2+ channels open and calcium ions enter
  • Calcium ions cause synaptic vesicles to fuse with presynaptic membrane and release ACh/NT
  • ACh/NT diffuses across synaptic cleft
  • ACh binds to receptors on the postsynaptic membrane
  • Sodium ions enter postsynaptic neurone leading to depolarisation
19
Q

Role of oestrogen in transcribing target gene (5)

A
  • Oestrogen diffuses through the phospholipid bilayer as it’s lipid soluble
  • Diffuses through nuclear envelope
  • Binds to ERa repceptor
  • ERa receptor changes shape/ 3’ structure
  • Causes release of transcription factor
  • Transcription factor binds to promoter region of DNA
  • Stimulates RNA polymerase to bind to DNA and initiate transcription of gene
  • Produces mRNA
20
Q

Muscle contraction / Sliding filament theory / Shortening of sarcomeres (5)

A
  • Ca2+ released from sarcoplasmic reticulum
  • Ca2+ bind to troponin and cause tropomyosin to move
  • Exposes myosin head binding sites on actin
  • Actinomyosin cross-bridge forms
  • Myosin head pulls actin a short distance over myosin (POWER STROKE)
  • ADP + Pi are released from the myosin head
  • A new ATP molecule binds to myosin head and breaks cross-bridge
  • ATP is hydrolysed to ADP + Pi by ATP hydrolase (activated by Ca2+) - energy released returns myosin head to its original position
    (Ca2+ actively transported into sarcoplasmic reticulum)
21
Q

Semi conservative DNA replication (5)

A
  • DNA strands separate / H-bonds break
  • Each strand acts as a template
  • Free DNA nucleotides align by complementary base pairing (A-T and C-G)
  • DNA polymerase joins adjacent nucleotides on developing strand by condensation reactions, and forms phosphodiester bonds
  • Each new DNA molecule has 1 old strand and 1 new strand
22
Q

Role of receptors + nerves in the control of HR (5) (to increase HR)

A
  • Chemoreceptors detect rise in CO2/acidity
    OR Baro-receptors detect rise in blood pressure
  • Send impulses to medulla oblongata
  • More impulses to SAN
  • Via sympathetic nerve (for chemoreceptors)
  • Via parasympathetic nerve (for baro-receptors)
23
Q

Action of ADH in kidney (5)

A
  • ADH bind to target cell membrane receptor proteins on cells lining DCT and CD
  • Permeability of cells to water is increased
  • More water absorbed from DCT/CD into blood
  • by osmosis
  • Smaller volume of urine produced
  • Urine becomes more concentrated
24
Q

How insulin reduces blood glucose concentration (5)

A
  • Insulin binds to complementary receptors on target cells membrane
  • Stimulates uptake of glucose by glucose channel proteins
  • Activates liver + muscle enzymes that convert glucose to glycogen
25
Q

How the movement of substances across cell membranes is affected by membrane structure. (5)

A

· Phospholipid (bilayer) allows movement/diffusion of non-polar/lipid-soluble substances;
· Phospholipid (bilayer) prevents movement/diffusion of polar/ charged/lipid-insoluble substances OR (Membrane) proteins allow polar/charged substances to cross the membrane/bilayer;
· Carrier proteins allow active transport; · Channel/carrier proteins allow facilitated diffusion/co-transport;
· Shape/charge of channel / carrier determines which substances move;
· Number of channels/carriers determines how much movement;
· Membrane surface area determines how much diffusion/movement;
· Cholesterol affects fluidity/rigidity/permeability;

26
Q

Describe how substances can cross a cell surface membrane. (5)

A

1 (Simple / facilitated) diffusion from high to low concentration / down concentration gradient;
2 Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer; OR Large / polar / water-soluble molecules go through proteins;
3 Water moves by osmosis / from high water potential to low water potential / from less to more negative water potential;
4 Active transport is movement from low to high concentration / against concentration gradient;
5 Active transport / facilitated diffusion involves proteins / carriers;
6 Active transport requires energy / ATP;
7 Ref. to Na+ / glucose co-transport;

27
Q

Explain how water enters xylem from the endodermis in the root and is then transported to the leaves. (6)

A

(In the root)
- Active transport by endodermis;
- (Of) ions/salts into xylem;
- Lower water potential in xylem / water enters xylem by osmosis /down a water potential gradient;

(Xylem to leaf)
- Evaporation / transpiration (from leaves);
- (Creates) cohesion / tension / H-bonding between water molecules / negative pressure;
- Adhesion / water molecules bind to xylem;
- (Creates continuous) column of water

biology (18 decks)

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