Extended Answer Questions Flashcards
(a) Briefly describe the role of an enzyme and explain how an enzyme’s function can be altered due to the presence of other molecules.
Role of an enzyme
-The role of the enzyme is to be a biological catalyst
-lower the activation energy of chemical reactions
-to not be consumed and to be reused in reactions
-increase the rate of reactions and to speed up biochemical process
- they are specific for specific enzyme meaning they only attach to a specific active site
-represented by the lock and key model
Factors affecting function
How it can be altered
-inhibitors
-co enzymes
-organic molecules and other molecules which bind to the active site helping the enzyme bind to the active site and change the shape off the enzyme
-concentration is increased there will be an increase number off collisions meaning reactions occur faster
(b) By referring to the specialised cell which produces gastric enzymes and describe the role of the gastric enzymes to supply soluble nutrients.
chief cells secrete pepsinogen which is in active it is activated by the acidic ph of the hydrochloric acid it then becomes pepsin which will break down proteins into amino acids
Gastric lipase then digests fats and removes fatty acid from triglycerides the proteins and fats are then absorbed in the small intestine
Describe in detail the nature and location of the chemical processes involved in aerobic respiration
- Energy yielding
- Involves conversion of oxygen and glucose to carbon dioxide and water
- Energy produced in the form of high energy bonds/ATP
- 36-38 ATP molecules produced from one glucose molecule.
- Description of Krebs cycle/ glycolysis
- First stage/ glycolysis takes place in cytoplasm
- Later stages take place in mitochondria/ inner membrane of mitochondria
- Most ATP produced in mitochondria/ less in cytoplasm
(b) Digestion involves the breakdown of large molecules into smaller ones so that nutrients can be supplied to cells in a form that can be used for metabolic processes. Explain how carbohydrates, proteins and fats are mechanically and chemically digested
- mechanical Chewing/mastication in mouth
- Churning in stomach
- Peristalsis in small intestine
- Bile salts emulsify fats
•chemical digestion of carbohydrates Chewing/mastication in mouth • Churning in stomach • Peristalsis in small intestine • Bile salts emulsify fats
chemical digestion of proteins
• Pepsin /gastric protease in stomach breaks proteins to polypeptides
• Pancreatic protease breaks polypeptides into peptides/ peptones
• Intestinal juice contains peptidases to break peptides into amino acids
chemical digestion of fats Fats Chemical:
• Pancreatic juice contains lipases which break lipids into fatty acids and glycerol
• Intestinal juice contains lipases which break down lipids to fatty acids and glycerol
(b) Digestion involves the breakdown of large molecules into smaller ones so that nutrients can be supplied to cells in a form that can be used for metabolic processes. Explain how carbohydrates, proteins and fats are mechanically and chemically digested
- mechanical Chewing/mastication in mouth
- Churning in stomach
- Peristalsis in small intestine
- Bile salts emulsify fats
•chemical digestion of carbohydrates Chewing/mastication in mouth • Churning in stomach • Peristalsis in small intestine • Bile salts emulsify fats
chemical digestion of proteins
• Pepsin /gastric protease in stomach breaks proteins to polypeptides
• Pancreatic protease breaks polypeptides into peptides/ peptones
• Intestinal juice contains peptidases to break peptides into amino acids
chemical digestion of fats Fats Chemical:
• Pancreatic juice contains lipases which break lipids into fatty acids and glycerol
• Intestinal juice contains lipases which break down lipids to fatty acids and glycerol
Excess proteins are broken down in the body. The nitrogenous waste compounds produced from these proteins are then excreted. Describe the processes involved in breaking down proteins. Include in your answer a description of how and where the nitrogenous waste compounds are produced, how they are transported and how they are excreted.
How and where broken down • Proteins broken down to amino acids • Amino group removed from amino acid • Converted to ammonia • Ammonia converted into urea by adding CO2 • Deamination occurs in the liver
How transported:
• Urea moves into blood plasma
• Transported to kidneys
How excreted- Any 3 of the following
• Filtration occurs in glomerulus
• Urea moves into Bowmans capsule
• Urea diffuses into filtrate in other regions of the nephron
• Urine containing urea excreted out of body via urethra
• Small amounts also lost as sweat
Pepsin is an enzyme that is released into the acidic environment of the stomach.
Pepsin assists the breakdown of proteins to amino acids. Explain how changes in
temperature and pH levels of the stomach will affect the action of pepsin in breaking
down proteins.
Temperature
• Pepsin needs optimum temperature/ about 37⁰C
• Increases in temp will denature enzymes as they are proteins
• This will alter the shape of the active site
• causing the substrate to not fit in the active site and prevent protein break down
• Decrease in temp will reduce the kinetic energy of enzymes and substrate
• leading to less possible contact between proteins and pepsin/ enzyme action slows
• and therefore, less amino acids being produced
pH:
• Pepsin will work most effectively at optimal pH/ acidic pH
• Altering the pH from the optimal alters the shape of the active site/causes denaturation
• leading to less amino acids being produced from the breakdown of proteins
• Significant increase or decrease in pH levels will terminate all pepsin action
The male reproductive system consists of a number of structures that all contribute to the production and transport of sperm. Name and explain the role of the three accessory glands found in the male reproductive system
Names
• Seminal vesicles
• Prostate gland
• Cowper’s/ Bulbourethral gland
1-3 Seminal vesicles • Secretes a thick alkaline fluid • Rich in sugar • Provides energy for sperm cells
1-3 Prostate gland • Secretes a thin milky fluid • Alkaline • Neutralises the acidity of vagina / cervical fluids 1-3 Cowper’s gland • Secrete mucous • For lubrication of sperm / aid movement of sperm 1-2
Lifestyle choices of a pregnant woman can often affect the development of a foetus. Explain how drinking alcohol, smoking cigarettes, and dietary choices can impact foetal development.
Alcohol- Any 3 of the following
• Teratogen.
• Foetal alcohol syndrome (FAS)/ Foetal alcohol spectrum disorder (FASD).
• Malformations of foetus.
• Foetal nervous system development affected.
• Under nourishment of foetus.
• Facial deformations.
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Smoking- Any 3 of the following • Changes to baby’s brain and lungs • Reduced oxygen supply • Retarded growth and development • Increased risk of cleft palate and lip
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Diet- Any 2 of the following
• Lack of folic acid can lead to spina bifida and other neural tube defects/ autism
• Lack of calcium in the diet / deficiency of Vitamin A can lead to bone deformities.
• Listeriosis / Listeria infection caused by eating contaminated food may cause miscarriages or stillbirths.
• High mercury from fish may have effects on brain and nervous system
Accept any other reasonable answers
Describe the structure of DNA and the main steps in DNA replication
Structure- any 5 of the following
• DNA consists of nucleotides
• Nucleotide consists of a sugar, phosphate and a nitrogenous base
• The DNA molecule is in the form of a double-helix
• The nitrogenous bases are Adenine(A), Thymine(T), Guanine(G) and Cytosine(C)
• The backbone is made up of a deoxyribose sugar and phosphate
• They pair in the following manner A-T/T-A/ and C-G / G-C complementary base pair rule
• Held together by weak hydrogen bonds
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Replication- any 6 of the following
• Enzyme (DNA helicase) breaks hydrogen bonds
• The double-stranded DNA unwinds/separates
• Each of the two DNA strands /molecules is copied/acts as a template/becomes half of the new DNA molecule.
• Free nucleotides move in
• Nucleotides bond with complementary bases
• Synthesis occurs in one direction only
• Enzyme (DNA polymerase) seals nucleotides to each other
• Ligase joins short stretches of DNA together
• Semi-conservative process/ Okazaki fragments/ leading and lagging strands.
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During embryonic development the inner cell mass of the blastocyst will differentiate. The name given to a cell that can differentiate into any type of tissue is a ‘stem’ cell. Name the 3 types of stem cells, describe their potency and explain where they can be found
Name Potency Location Mark
Totipotent Can become any type of cell necessary for embryo and embryonic membranes Zygote
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Multipotent Develop into a cell of a particular tissue type In embryos and adult tissue 1-3
Pluripotent Can become any type of cell that make up the human body Inner cell mass of blastocyst 1-3
In the human body the functioning of the different body systems is closely related to the structure of the tissues and organs that connect together to create the system. For each of the following describe the structure of the component and identify how the structure is responsible for the functioning of the system in which it is found.
alveolus
Alveolus Structure : Any two of the following
• Thin single celled/simple squamous epithelial cells
• Highly permeable membrane
• Highly vascularised/surrounded by capillaries
• Moist
Functioning: Any two of the following • Site of gas exchange • Allows for diffusion of gases • High surface area to volume ratio to allow for rapid diffusion of gases • Close association with capillaries to allow for gas transfer
Nephron
Structure: Any two of the following
• Comprised of renal tubules and glomerulus/renal corpuscle
• Surrounded by blood vessels/ peritubular network
• DCT of different nephrons join into collecting ducts
Functioning: Any two of the following
• Filtration of substances from the blood
• Reabsorption of essential materials (such as glucose and amino acids)
• Tubular secretion of materials(such as penicillin/ H+)
• Creates urine
• Removes metabolic wastes
villus Structure : Any two of the following • Finger like/hair-like projections • Has microvilli • Single cell layer/simple columnar epithelium • Capillary bed and lacteals • Contains goblet cells
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Functioning: Any two of the following
• Large SA to increase absorption
• Absorbs water by osmosis into capillaries
• Absorbs amino acids/glucose by active transport into blood
• Absorbs fatty acids and glycerol/ fat soluble vitamins into lacteals
• Secretes mucous to allow for peristalsis
• Peristalsis moves food through alimentary canal.
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