Essay Questions Flashcards
Discuss the factors that affect enzyme activity
- Enzymes are catalysts/seed up metabolism/chemical reaction/lower activation energy
- Temperature: enzymes have an optimum temperature/temperature at wrich they work best/work best at 37°C (or labelled graph to illustrate)
- pH: all enzymes have an optimum pH/pH at which they work best (or labelled graph to illustrate)
- Denaturing: a change occurs in the structure/shape/active site of the enzyme at high temperatures/when the pH changes
- Inhibitors: slow up/stop enzyme activity
- Competitive inhibitors: allach to/block the active site so keeping out the substrale molecule OR inhibitor competes with substrate for active site
- Non-competitive inhibitors: attach to another part of an enzyme and changing the shape of the active site/enzyme (so the substrate molecule does not fit)
- Substrate concentraton: increasing substrate concentration increases activity until a point when activity levels off (or labelled graph to lustrate)
- Explanation that activity levels off when al enzyme active sites are reacting with substrate molecules/enzymes are working at fastest rate possible
- Enzyme concentration: increasing enzyme concentration increases the rate of reaction (or labelled graph to illustrate)
- Explanation that activity increases due to more active sites being added
Give an account of cell differentiation under the following headings.
(i) Stem cells;
(ii) Somatic cells;
(iii) Germline cells.
Stem cells
- Differentiation occurs when unspecialised cells become specialised (to perform a specific function)
- Stem cells are unspecialised cells that can (divide to) form more stem cells
- Embryonic stem cells can differentiate / develop into all / any cell types
- Tissue / adult stem cells give rise to a more limited range of / fewer cell types
- Example given such as stem cells in the (red) bone marrow only produce blood cells / named blood cells
- A differentiated cell only has a few genes switched on / produces specific proteins
Somatic cells
- Somatic cells form different types of body tissue
- Body organs are formed from a variety/mixture of these tissues
- (The nucleus of a) somatic cell divides by mitosis (to maintain the diploid chromosome number)
Germline cells
- The (nucleus of a) germline cell can divide by mitosis to produce more germline cells / diploid cells
- (The nucleus of a) germline cell can divide by meiosis to produce haploid gametes/ cells.
- Mutations in germline cells can be passed on to offspring (whereas mutations in somatic cells are not).
Describe protein synthesis under the following headings:
(i) Transcription of DNA;
(ii) Translation of mRNA.
Transcription of DNA
1. DNA unzips/hydrogen bonds break/DNA strands separate.
2. RNA nucleotides pair with DNA bases.
3. Guanine pairs with cytosine, uracil pairs with adenine. (not base letters)
4. Sugar phosphate bonds form/sugar phosphate backbone forms.
5. This requires ATP/enzymes/RNA polymerase
6. Introns/non-coding regions are removed from mRNA/the primary transcript
Translation of mRNA
7. mRNA attaches/moves to the ribosome.
8. tRNA carries amino acid to mRNA /ribosome.
9. Each tRNA molecule is attached to a specific amino acid.
10. tRNA/mRNA has a anticodon/codon of three bases
11. Anticodon binds to / aligns with codon.
12. Order of codons/bases determines the order of amino acids.
13. Peptide bonds form between amino acids.
14. Ribosome moves along the mRNA strand.
15. (Translation/process) begins at a start codon/ends at a stop codon.
Describe aerobic respiration under the following headings:
(i) The citric acid cycle;
(ii) The electron transport chain.
The citric acid cycle
- Pyruvic acid/pyruvate is converted to an acetyl group.
- The acetyl group combines with coenzyme A (to form acetyl coenzyme A)
2a. Note - Breakdown of pyruvic acid to acetyl coenzyme A gets 1 mark only. - Acetyl coenzyme A combines with oxaloacetate/oxaloacetic acid to form citrate/citric acid.
- Citrate/citric acid is converted back into oxaloacetate/oxaloacetic acid / 4 carbon compound.
- Carbon dioxide is released.
- (Some) ATP is produced.
- Dehydrogenase (enzymes) remove hydrogen (ions)/(high energy)
electrons.
The electron transport chain
8. Hydrogen/electrons are passed to (coenzyme) NAD.
9.NADH release electrons to the electron transport chain.
10. Electrons are passed/cascade along the chain of carriers/proteins.
11. Energy is released which pumps hydrogen ions across the (inner)
mitochondrial membrane.
12.The return flow of hydrogen (ions) synthesises ATP.
13. Using the enzyme ATP synthase.
14. Oxygen acts as the final electron/hydrogen acceptor / combines with hydrogen.
15. Water is formed.
Describe the structure of DNA and the process of DNA replication.
Structure
1 DNA is composed of nucleotides containing deoxyribose (sugar), phosphate and base.
2 There is a sugar phosphate backbone.
3 The four bases are adenine, thymine, cytosine and guanine.
4 Cytosine bonds/pairs with Guanine and Adenine bonds with Thymine.
5 Bases/two strands are joined by hydrogen bonds.
6 Strands are anti-parallel/run in opposite directions/3’ to 5’ and 5’ to 3’.j
7 DNA/two strands form a double helix (shape).
Replication
DNA/double helix is unwound /unzipped.
A primer is needed at the start of replication/attaches to DNA strand.
C DNA polymerase adds
nucleotides to the 3’ end (of a new/growing strand/primer).
dOne strand is replicated continuously and the other strand is replicated in fragments/discontinuously.
e The strand replicated in fragments is joined together by ligase.
Describe the structure of RNA and the process of transcription.
Structure
1 RNA is single stranded.
2 It is composed of nucleotides containing ribose (sugar), phosphate and base.
3 The four bases are uracil, adenine, cytosine and guanine.
4 Groups of three bases/nucleotides form codons in mRNA/anticodons in tRNA.
5 Start/stop codons exist.
6 tRNA folds due to base pairing/has an attachment
7 site for a specific amino acid. rRNA (and protein) forms a ribosome.
Transcription
a. Transcription occurs in the nucleus.
b. RNA polymerase forms mRNA/ unwinds and unzips DNA.
c. (Complementary) base pairing, occurs - adenine with uracil, guanine with cytosine.
d. The primary transcript/mRNA contains introns and exons.
e Introns are removed/ exons remain after (RNA) splicing.
f (Splicing)forms the mature transcript/mRNA.
Describe hormonal control of the menstrual cycle under the following headings:
(i) events leading to ovulation;
(ii) events following ovulation.
i) 1. Pituitary gland secretes/ produces FSH/LH.
2. FSH stimulates growth of follicle (in the ovary).
3.Follicle/ovary produces oestrogen.
4. oestrogen stimulates growth/ repair proliferation / thickening of endometrium/ uterus lining.
5. Oestrogen stimulates production of LH.
6. LH (surge) brings about ovulation/release of the egg.
7. Rising/high levels of oestrogen inhibit FSH production.
8. This is negative feedback
(di)
a.The follicle develops into the corpus luteum.
b.Corpus luteum secretes progesterone (and ostrogen).
c. Progesterone maintains/ increases/thickens the endometrium/uterus lining.
d. Progesterone inhibits FSH/ LH production.
e. Progesterone/oestrogen levels decrease towards the end of the cycle.
f. This/corpus luteum degeneration triggers menstruation/breakdown of endometrium.
Describe the cardiac cycle under the following headings:
(i)the conducting system of the heart;
(ii)nervous control of the cardiac cycle.
- Pacemaker/SAN contains auto rhythmic cells/is where the heart beat originates/is found in the right atrium.
2 • Impulse/wave of excitation spreads across the atria/cause the atria to - (Impulses) reach/stimulate AVN.
- AVN found at junction of atria and ventricles at base of atria.
5.Impulses from AVN spread through ventricies. - (Cause contraction of ventricles/ventricular systole
- (This is followed by)
- relaxation/resting/diastolic phase/diastole
Discuss the causes, development and associated health problems of atherosclerosis.
Causes
Too much fat/cholesterol in the diet/blood. (1)
High LDL levels/low HDL levels or
High LDL:HDL or Low HDL:LDL.
Lack of exercise/inactive lifestyle.(1)
Genetic condition/familial hypercholesterolaemia/FH. (1)
Diabetes/ high blood glucose levels.(1)
Development
There is an accumulation of fatty/ fibrous material/ cholesterol/calcium.(1)
The atheroma/plaque forms beneath the endothelium of an artery.(1)
Artery (wall) thickens/ lumen narrows.(1)
Blood flow is reduced/ restricted/prevented.(1)
Loss of elasticity in artery (wall)/hardening of the artenes occurs.(1)
Health Problems
Raises blood pressure/causes hypertension.(1)
Causes CHD/angina/ heart attack/stroke/PVD (any 2). (1)
Description of CHD/angina/ heart attack/stroke/PVD.(1)
Discuss the diagnosis, treatment and role of insulin in Type 1 and Type 2
diabetes.
Diagnosis
Glucose presence in urine suggests diabetes.(1)
(Diagnosis made by carrying out a glucose tolerance test (1)
Individual fasts/does not eat prior to the test.(1)
Individual drinks a glucose solution/drink.(1)
Blood glucose concentration that remains high indicates diabetes. (1)
Type 1 diabetes tends to be diagnosed in children while type 2 diabetes tends to be diagnosed in adults/later in life.(1)
Treatment
Type 1 diabetes is treated with regular doses/ injections of insulin.(1)
Type 2 diabetes is treated/controlled by lifestyle changes/weight loss/exercise/ dietary changes.(1)
Role of Insulin
Insulin is produced in the pancreas.(1)
Type 1 diabetics are unable to produce insulin.(1)
Insulin converts glucose into glycogen.(1)
Type 2 diabetics can produce insulin but cells are less sensitive/ resistant to it.(1)
In Type 2 diabetics there are less insulin receptors on cells.(1)
Give an account of hormonal control of puberty and sperm production in
males.
- At puberty a (releaser) hormone is produced by the hypothalamus.
- The pituitary gland releases follicle stimulating hormone/ FSH and interstitial cell stimulating hormone /ICSH.
- FSH/ICSH acts on/targets the testes
- FSH stimulates sperm production in the seminiferous tubules.
- ICSH stimulates the production of testosterone in the interstitial cells.
- Testosterone stimulates sperm production
7.Sperm/gametes are produced from germline cells by meiosis. - Testosterone activates the prostate gland/seminal vesicles.
- Secretions affect/maintain sperm mobility/viability or named
example - Negative feedback control / feedback inhibition of sperm / testosterone production exists.
- High levels of testosterone inhibits /reduces/controls FSH/ICSH production.
Give an account of treatments for male and female infertility.
- Drug treatment / fertility drugs are used to stimulate/trigger ovulation/super ovulation.
- (Some) drugs prevent the negative feedback of ostrogen on FSH production.
- Other drugs mimic the effect of FSH/LH.
- Artificial Insemination is used if a man has a low sperm count
- (Several) sperm/semen samples are collected.
OR - Sperm can be provided bv a donor. sperm semen is inserted into the female reproductive tract by means other than sexual
7.intercourse / syringe.Intra-cytoplasmic sperm injection/ GS is used when man has a low sperm count/when sperm are defective. - The head of the sperm is (directly) injected/inserted into the egg.
- During In vitro fertilisation/IVF eggs are fertilised outside the body.
- Zygotes/fertilised eggs are
OR
Blastocysts/ balls of cells/ embryos are transferred into the uterus/womb. - Pre-implantation genetic diagnosis / PGD identifies genetic disorders/ chromosome abnormalities .
Discuss how cardiovascular disease occurs.
1 (Results of) cardiovascular disease include angina/stroke/heart attack/hypertension or high blood pressure/peripheral vascular disease.
Any 2 mentioned
2 Atherosclerosis is build-up of cholesterol/calcium/fatty/fibrous material in an artery.
3 Low density lipoproteins/LDLs transport cholesterol to the arteries.
4 An atheroma/plaque forms beneath the endothelium/lining of artery.
5 Artery thickens/hardens/loses elasticity/narrows.
6 Blood pressure increases / hypertension develops.
7 Atheroma can rupture and clotting factors are released.
8 Formation of a clot / thrombus occurs or thrombosis occurs.
9The clot/thrombus can break loose forming an embolus.
10 This can block arteries (causing a stroke/heart attack).
11Cells are deprived of oxygen.
12 A deep vein thrombosis (can occur) or DVT is a clot in a vein.
13 High blood glucose levels/diabetes can cause cardiovascular disease.
Discuss the screening and testing procedures which may be carried out as part of antenatal care.
- Mother’s blood pressure / blood type / blood tests / urine tests / general
health check
(any 2 named)
2.Ultrasound (imaging / scan) - Dating scan / scan at 8-14 weeks is used to determine stage of pregnancy / due date
4.Anomaly scan / scan at 18-20 weeks for serious physical problems - Biochemical / chemical tests detect (physiological) changes of pregnancy
6.Marker chemicals / named chemical can indicate medical conditions / can give a false positive result
7.Diagnostic / further testing can follow from routine testing / named test - Amniocentesis / cells from amniotic fluid used to produce karyotype / to test for Down’s Syndrome / chromosome abnormalities
- Chorionic villus sampling / CVS - cells from placenta / chorion used to produce karyotype / to test for Down’s syndrome / chromosome abnormalities
- If both amniocentesis and CVS named but no description given so not getting 8 or 9
11.CVS carried out earlier in pregnancy than amniocentesis - Allows immediate karyotyping
- CVS has higher risk of miscarriage
Discuss the exchange of substances between plasma and body cells.
1.Plasma is the liquid part of the blood
2.(Any 3) named dissolved substances carried - oxygen, carbon dioxide, glucose, amino acids, urea, vitamins, minerals, etc
3. Site of exchange is at the capillaries
4. Capillaries have a large surface area / thin walls / narrow diameter
5.High pressure (at the arterial end) forces fluid/plasma out of capillaries / pressure filtration
6.Tissue fluid (that bathes the cells)
7.Plasma proteins / blood cells do not pass through capillary walls / stay in blood
8. (Dissolved) substances diffuse / move from tissue fluid into body cells
9. Waste products / named example diffuse / move out of the cells
10. To be excreted / carbon dioxide breathed out
11. Liquid / water / tissue fluid returns into the plasma / blood
12. (Excess) tissue fluid enters lymphatic vessels/lymph
13. This lymph/ fluid is carried back to the blood (by lymphatic system ).