b2 Flashcards
(19 cards)
Give a definition of a catalyst?
A substance hat increases the rate of chemical reaction between two substances.
State three functions of proteins in living cells, other than acting as catalysts?
Building and repairing of body tissues, regulation of body processes and formation of enzymes.
Explain why an enzyme catalyzed reaction stops when the reaction mixture is heated above a certain temperature?
At low temperatures, enzyme reactions are slow. They speed up as the temperature rises until an optimum temperature is reached. After this point the reaction will slow down and eventually stop. enzyme activity increases steadily between 0 ºC and 40 ºC. It peaks at 40 ºC
In which three places in the body is amylase produced?
salivary glands, pancreas, small intestine
Where in the body is bile? a) Produced b) stored c) used?
The enzymes in the small intestine work best in alkaline conditions, but the food is acidic after being in the stomach. Bile is an alkaline substance produced by the liver and stored in the gall bladder. It is secreted into the small intestine, where it emulsifies fats.
Explain why the stomach produces hydrochloric acid?
This helps to begin digestion, and it kills many harmful microorganisms that might have been swallowed along with the food. The enzymes in the stomach work best in acidic conditions - in other words, at a low pH
Write down the word equation for aerobic respiration?
Glucose + oxygen = carbon dioxide + water(+energy)
Give two examples of how an animal uses the energy released by aerobic respiration?
Most of the chemical reactions involved in the process happen in tiny objects inside the cell cytoplasm, called mitochondria. The energy released by respiration is used to make large molecules from smaller ones. In plants, for example, sugars, nitrates and other nutrients are converted into amino acids.
What is anaerobic respiration? give the word equation for anaerobic respiration in our bodies.
Anaerobic respiration is a form of respiration using electron acceptors other than oxygen. glucose → lactic acid (+ energy released)
Explain how you repay an oxygen debt?
Take in more oxygen to refill the glycogen stores
Give two kinds of enzyme that would be useful in biological washing powder?
Biological detergents and washing powders use lipases and proteases to break down fat and protein
molecules from food stains that have remained on clothing.
Discuss the advantages and disadvantages of using enzymes in industry?
Advantages of enzymes:
Their function is characterised by specificity. Enzymes are very specific as to which reaction they are catalysing and which substrate or molecule they are working on.
They reduce the activation energy of reactions and increase their speeds, sometimes by a factor of millions when compared to un-catalysed reactions.
They work in mild conditions - low temperatures, neutral pH and normal atmospheric pressure. This saves a lot of energy.
They help to speed up digestion processes in the human body.
Disadvantages of enzymes:
They are highly responsive to changes in physical and chemical conditions surrounding them. It is difficult to manipulate their working.
They are easily denatured by even a small increase in temperature and are highly susceptible to presence of other chemical substances and changes in pH. The conditions in which they work must be tightly controlled.
Enzymes are difficult to work with as substrate mixtures must be uncontaminated with other substances that might influence the reaction.
The high cost of enzyme isolation and purification discourages their use, especially in areas which currently have an established alternative procedure.
Explain how DNA controls the activities of a cell?
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The nucleus of a cell contains chromosomes, which carry genetic information in a long molecule called DNA. Genes are regions of DNA that carry the code to control a particular cell activity or the production of a particular protein.
Explain how DNA fingerprinting is used in forensic science?
The term DNA fingerprinting - or genetic fingerprinting - is applied to the scientific process whereby samples of DNA are collected, collated and used to match other samples of DNA, which may have been found at the scene of a crime
What is mitosis used for in the human body? Describe the four steps mitosis?
Mitosis is used for growth and repair and produces diploid cells identical to each other and the parent cell.
Mitosis is simply described as having four stages—prophase, metaphase, anaphase, and telophase.
Name the other type of cell division, and say where it happens in the body of a human male?
Meiosis is a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells. This process is required to produce egg and sperm cells for sexual reproduction.
What is differentiation in a cell?
In developmental biology, cellular differentiation is the process by which a less specialized cell becomes a more specialized cell type. Different tissues have different kinds of cells
Give three ways that embryonic stem cells could be used to cure diseases?
Replace neurons damaged by spinal cord injury, stroke, Alzheimer’s disease, Parkinson’s disease or other neurological problems;
produce insulin that could treat people with diabetes and heart muscle cells that could repair damage after a heart attack;
Which chromosomes in the human body causes, male characteristics?
sex cells-sperm
