B3 Living And Growing Flashcards
1
Q
Where does respiration occur to provide energy for life processes
A
Mitochondria
2
Q
What is the purpose of chromosomes and what it is made of?
A
- carry coded information in the form of genes
- made of a molecule called DNA
3
Q
Define genetic code
A
Information in the genes in the form of coded instructions
4
Q
Genetic code controls all cell activity and consequently some characteristics of the organism
A
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5
Q
DNA controls the production of different proteins
A
-
6
Q
Proteins are needed for the growth and repair of cells
A
-
7
Q
Which scientists first discovered the structure of DNA
A
Watson and Crick
8
Q
Explain why liver and muscles have large numbers of mitochondria
A
- liver cells need a lot of mitochondria as they require lots of energy as they carry out many reactions.
- muscles cells need a lot of mitochondria because they require a lot of ATP for contraction
9
Q
Some structures in cells, such as ribosomes can’t be seen with a light microscope.
Ribosomes are in the cytoplasm and are the site of protein synthesis
A
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10
Q
Describe the structure of DNA
A
Two strands coiled to form a double helix, each strand containing chemicals called bases, of which their are 4 different types, with cross links between the strands formed by pairs of base
11
Q
Describe chromosome
A
Long coiled molecules of DNA, divided up into regions called genes
12
Q
DNA has four bases : A, T, C, G. What are the complementary base pairings?
A
AT
CG
13
Q
Explain how protein structure is determined by the DNA base code
A
- the base sequence determines amino acid sequence
- each amino acid is coded for by a sequence of 3 bases
14
Q
Each gene:
- contains a different sequence of bases
- codes for a particular protein
A
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15
Q
Where are proteins made and by why is a copy of the gene needed?
A
Proteins are made in the cytoplasm and a copy is needed because the gene itself cannot leave the nucleus
16
Q
Explain how the code needed to produce a protein is carried from the DNA to the ribosomes by a a molecule called mRNA
A
The mRNA is a single-stranded molecule. It is a copy of one strand of a length of DNA.
17
Q
Explain how DNA controls cell function by controlling the production of proteins, some which are enzymes
A
Enzymes control all the chemical reactions in your cells. So the genetic code controls the cell. As a consequence it controls most of your characteristics.
18
Q
Describe how Watson and Crick used data from other scientists to build a model of the DNA
A
X-ray data showing that there were two chains wound in a helix
Data indicating that the bases occurred in pairs
19
Q
Explain why new discoveries are not accepted or rewarded immediately
A
Other scientists have to repeat the work and verify it
It is not clear, straight away how important and useful the discovery is
20
Q
The genes in a cell that are switched on determine the function of a cell
A
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21
Q
Give some examples of proteins
A
Collage
Insulin
Haemoglobin
22
Q
Describe enzymes
A
Enzymes are protein molecules that speed up a chemical reaction and work best at a particular temperature
23
Q
Enzymes have active sites that the substrate molecules fit into when a reaction takes place
A
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24
Q
Different cells and organisms will produce different proteins
A
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25
Describe gene mutations
Changes to genes
26
What are proteins made of?
Long chains of amino acids
27
Describe some functions of proteins
Structural-Collagen
Hormones-insulin
Carrier molecules-haemoglobin
Enzymes
28
How do proteins differ from each other
Each protein has its own number and sequence of amino acids, which results in differently shaped molecules which have different functions
29
Describe enzymes
Biological catalyst which catalyses chemical reactions occurring in the living cells (respiration, photosynthesis, protein synthesis) which have a high specificity for their substrate
30
What are anabolic and catabolic enzymes
Anabolic catalysts are used to build structures where as catabolic catalysts are used to break structure (Glucose breakdown)
31
Explain the specificity of enzymes in terms of the "lock and key" mechanism
Each enzyme is specific for its substrate molecule just like a key is specific for a lock
32
Describe the rate of reaction of an enzyme-catalysed reaction will change by increasing/decreasing temperature and changing the pH
By increasing the temperature, the rate of reaction will increase as the enzymes and substrates move more quickly and collide more often ( doubles after each 10'C). However after an extent, the enzymes denature. ( the shape of the active site changes, the substrate molecule can no longer fit in the active site, the rate of reaction decreases and eventually stops).
By lowering the temperature, there are lower collision rates, meaning the enzyme has become inactive.
If the pH is altered, the shape of the active site changes, meaning the substrate can't fit in the active site, meaning the enzyme has denatured.
33
Gene mutations may lead to the production of different proteins.
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34
How can gene mutation occur?
- exposure to radiation or chemicals
| - spontaneously
35
Only some full set of genes are used in any one cell; some genes are turned off
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36
Mutations can be useful, neutral or harmful
Useful : pale skins are caused by mutations, it would be useful for people who live in temperate regions of the world. It allows their skin to make vitamin D because the weaker sunlight can only penetrate through paler skin.
Harmful: cells to continue to divide (cancer), slightly differently shaped haemoglobin molecules (anaemia)
Neutral: being able to roll your tongue, free or attached earlobes
37
Explain how changes to genes alter or prevent the production of the protein which is usually made
Changes to gene involves the shape of an enzyme to change, meaning the enzyme can not longer catalyse the chemical reaction it used to do, now it can catalyse a new reaction due to the substrate not being able to fit in the new active site
38
The energy provided by respiration is needed for all life processes in plants and animals
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39
Word equation for aerobic respiration
Glucose + oxygen ---> carbon dioxide + water
40
Describe examples of life processes that require energy from respiration
Muscle contraction
Protein synthesis
Control of body temperature in mammals
41
Explain why breathing and pulse rates increase during exercise
During exercise your muscle needs more oxygen per minute as it produces more carbon dioxide per minute.
The heart rate and pulse rate goes up to deliver more oxygen and glucose to your muscles per minute. Your breathing rate also goes up to remove the excess carbon dioxide quickly.
42
Symbol equation for aerobic respiration
C6H12O2 + 602 ----> 6CO2 + 6H2O + ATP
43
Oxygen consumption increases when Carbon Dioxide production increases
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44
Respiration results in the production of ATP and ATP is used as an energy source for many processes in the cell
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45
Explain how the rate of oxygen consumption can be used as an estimate of metabolic rate because aerobic respiration requires oxygen
As aerobic respiration requires oxygen, the amount of oxygen an organism uses in a particular period of time indicates its metabolic rate. The metabolic rate is a measure of how quickly all the chemical reactions are going on in the organism's body.
46
Explain why the rate of respiration is influenced by the changes in temperature and pH
Not sure
47
Explain fatigue in terms of lactic acid being built up and how this is removed during recovery
Hard exercise causes lack of oxygen in cells
The incomplete breakdown of glucose
Continued panting replaces oxygen allowing aerobic respiration
Increased heart rate ensuring that blood carries lactic acid to the liver to be broken down
48
Explain why anaerobic respiration occurs during hard exercise in addition to aerobic respiration
When you start hard exercise, your heart does not go up quickly enough to provide the extra oxygen. To make up for the shortfall in energy release, your muscles cells use both types of respiration
49
Disadvantages of anaerobic respiration
Produces lactic acid
| Accumulation of this can cause muscles pain and fatigue
50
Word equation of anaerobic respiration
Glucose ----> Lactic Acid + ATP
51
Anaerobic respiration release less energy per glucose molecule than aerobic respiration
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52
Describe the difference between simple organisms and complex organisms
Simple organisms are unicellular
| Complex organisms are multicellular
53
Most body cells contain chromosomes in matching pairs
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54
Why do chromosomes need to be copied to produce new cells for growth?
Before a cell divides, its genetic material can be copied so that each cell has a complete set of genetic material. Each chromosome, made of one molecule of DNA is copied. So before a cell divides, each molecule of DNA copies itself. This is called DNA replication
55
What is the purpose of Mitosis
To replace worn out cells
To repair damaged cells
Asexual reproductions
56
During sexual reproduction the gametes join in fertilisation: when the egg is fertilised by the sperm
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57
Gametes have half the number of chromosomes of body cells
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58
In sexual reproduction, to produce unique individuals, half the genes come from each parent
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59
Explain why sperms are produced in large numbers
To increase chance of fertilisation
60
Explain the advantages of being multicellular
Allows organism to be larger
Allows for cell differentiation
Allows organism to be more complex
61
Explain why becoming multicellular requires the development of specialised organ systems.
Communication between cells
Supplying the cells with nutrients
Controlling exchanges with the environment
62
New cells for growth are produced by mitosis
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63
Explain why cells produced by mitosis are identical
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64
In mammals, body cells are diploid (2 copies of each chromosome)
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65
Explain why DNA replication must occur before cells divide
To ensure each cell has a complete set of genetic material
66
Describe how DNA replication occurs
DNA is a double-stranded molecule
The molecule unzips and forms two new strands
This exposes the DNA bases on each strand
Spare DNA bases in the nucleus line up against each separated strand of DNA
They only align next to their complementary DNA base, forming base pairs
One molecule of DNA has become two identical molecules
67
Describe how in mitosis the chromosomes
Line up along the centre of the cell
They then divide
The copies move to opposite poles of the cell
68
Gametes are produced by meiosis
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69
Describe gametes
Gametes are haploid (contain one chromosome from each pair)
70
Explain why fertilisation results in genetic variation
Gametes combine to form a diploid zygote
| Genes on the chromosomes combine to control the characteristics of the zygote
71
Explain how the structure of the sperm is adapted to its function
Many mitochondria to provide energy
An acrosome that releases enzymes to digest the egg membrane
Are small and have a tail so they can swim to the egg
Have a nucleus to carry their genetic material
72
Explain why in meiosis the chromosome number is halved and each cell is genetically different
One chromosome from each pair separate to opposite poles of the cell in the first division
Chromosomes divide and the copies move to opposite poles of the cell in the second division
73
Describe the functions of the components of the blood
Red blood cells : to carry oxygen
White blood cells : defend body against diseases, some ingest bacteria or viruses, some produce antibodies
Platelets : hell your blood clot when a cut occurs
74
How are red blood cells adapted to their function?
Small in size and relatively thick- can fit through capillaries one at a time
Large SA compared to its volume meaning it can carry more oxygen
Shape- biconcave discs SA/V Ratio even more
No nucleus- more room for haemoglobin, more oxygen carried
Contains haemoglobin which reacts with oxygen to form oxyhaemoglobin. At respiring cells, oxyhaemoglobin is broken down into oxygen and haemoglobin
75
What does the plasma consist of?
Digest food
Hormones
Antibodies
Cholesterol
76
Describe the functions of the heart in the pumping of the blood
The right side of the heart pumps blood the the lungs
| The left side of the heart pumps the blood to the rest of the body
77
Types of blood vessels
Veins
Arteries
Capillaries
78
Blood in the arteries is at higher pressure than blood in the veins
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79
Describe how different parts of the circulatory system work together
Arteries transport blood away from the heart
Veins carry blood to the heart
Capillaries exchange materials with tissues
80
State any adaptations of arteries, veins and cappilaries
Thick muscular and elastic wall in the arteries
Large lumen and presence of valves in veins
Permeability in capillaries
81
Identify parts of the heart and their functions
Left and right ventricles pump blood
Left and right atriums receive blood
Semilunar, bicuspid and tricuspid valves prevent back flow of blood
Four main blood vessels of the heart: vena cava, aorta, pulmonary artery and pulmonary vein
82
Explain why the left ventricle has a thicker wall muscle than the right ventricle
Because the left ventricle has to pump blood further than the right ventricle has to
83
Explain the advantages of having a double circulatory system
Higher pressure
| Therefore greater rate of flow to the tissues
84
Describe the functions of parts of a plant cell
- vacuole, containing cell sap and provide support
| - the cell wall, made of cellulose to provide support
85
Describe how to make a stained slice of an onion cell
Not sure ask on Saturday
86
Bacterial cells are smaller and simpler than plant and animal cells
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87
Growth can be measured as an increase in height, wet mass or dry mass
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88
Describe the process of growth
Cell division followed by cells becoming specialised
89
What is the process of cells becoming specialised
Differentiation
90
Animals grow in the early stages of life whereas plants grow continually
All parts of animals are involved in growth whereas plants grow at specific parts of the plant
91
Differences between bacterial and , plants and animal cells
Bacterial cell lacks:
A true nucleus
Mitochondria
Chloroplasts
92
Describe the difference between the arrangement of DNA in a bacterial cell and a plant/animal cell
Presence/absence of a nucleus
| Single circular strand/chromosomes
93
Dry mass is the best method of measuring growth
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94
Describe the main phases of a typical growth curve
Infancy - growth is rapid after birth
Childhood - growth slows to a steady rate
Adolescence - puberty causes sudden growth
Adulthood - growth rate falls to zero
95
Undifferentiated cells are called stem cells
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96
Stem cells can develop into different cells, tissue and organs
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97
Stems cells can be obtained from embryonic tissue and can be used to treat medical conditions
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98
Describe issues arising from stem cell research in animals
Use of embryonic stem cells raises ethical issues as the spare embryos used could have developed into people. However, without stem cell research these embryos would still be discarded.
99
Explain the difference between adult and embryonic stem cells
Adult stem cells cannot differentiate in to as many different type of cells
100
Explain why plant growth differs from animal growth
- Animals tend to grow to a finite size but many plants grow continuously
- Plant cell division is mainly restricted to areas called meristems
- Cell enlargement is the main method by which cells gain height
- Many plant cells retain the ability to differentiate but most animal cells lose it at an early stage
101
Describe the process of selective breeding
- selection of described characteristics
- cross breeding
- selection of suitable offspring over may generations
102
Explain how selective breeding can contribute to improved agricultural yields
-NOT sure ask
103
Selected genes can be artificially transferred from one living organism to another
This transfer of genes is called genetic modification or genetic engineering
The transfer of genes can produce organisms with different characteristics
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104
Features of animals that may be desirable
```
Animals which have more muscle and less fat for lean meat
Produce higher milk yields
Lay more eggs
Reach maturity quicker
Have more wool
Can run faster
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105
Selective breeding programmes may lead to interbreeding, which can cause health problems with the species
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106
Explain how selective breeding programme may reduce the gene pool leading to problems of interbreeding
Accumulation of harmful recessive characteristics
| Reduction in variation
107
Explain some potential advantages and disadvantages of selective breeding programmes
Organisms with desired qualities are produced rapidly
Inserted genes may have unexpected harmful effects
108
Describe some examples of genetic engineering
The production of human insulin is a genetically engineered bacteria
Transferring resistance to herbicides, frost damage or disease to crop plants
109
What are the principles of genetic engineering
Selection of desired characteristics
Isolation of genes responsible
Insertion of the genes into other organisms
Replication of these genes
110
What is gene therapy?
Changing a person's genes in an attempt to cure disorders
111
Gene therapy can involve body cells or gametes
-
112
Cloning is an example of asexual reproduction
| Cloning produces genetically identical properties
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113
Dolly the sheep was the first mammal to be cloned from an adult
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114
Identical twins are naturally occurring twins
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115
Plants grown from cuttings or tissue culture are clones
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116
Potential benefits:
•Creation of replacement organs
and tissues.
•Could allow infertile parents to
have children.
•Extending life by replacing
ageing tissues and organs.
-
117
Potential issues:
•Humans created as tools or
products for medicine.
•Clones would be identical twins
of the cell donor.
•Research to perfect cloning
could lead to damaged clones.
•Decreasing genetic diversity
caused by asexual cloning.
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118
Describe how to take a cutting
Cut a bit of the stem or roots and grow it in to a new plant
119
Describe how spider plants, potatoes and strawberries reproduce asexually
Produces special stems called runners. New plants, clones of the parent, develop at the end of each runner.
Produces runners like the strawberry plant. The new plantlets can be planted.
Produces tubers (swollen parts of underground stems). If not eaten, each potato tuber could produce a genetically identical new plant.
120
Dolly the sheep was produced by the process of nuclear transfer and that nuclear transfer involves placing the nucleus of a body cell in to an egg cell
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121
Describe some possible uses of cloning
Mass producing animals with desirable characteristics
Producing animals that have been genetically engineered to provide human products
Producing human embryo to supply stem cells for therapy
122
Describe the cloning technique used to make Dolly the sheep
Nucleus is removed from an egg cell
Egg cell nucleus is replaced with the nucleus from an udder cell
Egg cell given an electric shock to make it divide
Embryo implanted into a surrogate mother sheep
Embryo grows into a clone of the sheep from which the udder cell came
123
Animals like pigs can be modified to produce replacement organs for human transplants
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124
Describe the advantages and disadvantages associated with the commercial use of cloned plants
Advantages: can be sure of characteristics of the plant since it will be genetically identical
Advantages: it is possible to mass produce plants that may be difficult to grow seed from
Disadvantages: if plants become susceptible to disease or to change in environmental conditions then all plants will be affected
Disadvantages: lack of genetic variation
125
Describe plant cloning by tissue culture
Selection from characteristics
Large number of small pieces of tissues
Aseptic technique
Use of suitable growth medium and conditions
126
Explain why cloning plants is easier than cloning animals
Many plant cells retain ability to differentiate unlike animal cells which usually lose this ability at an early stage
