B3 Flashcards
1
Q
What 6 cell structures are found in a plant cell?
A
Nucleus Cytoplasm Chloroplasts Cell wall Vacuole Cell membrane
2
Q
What 4 cell structures are found in bacterial cells?
A
Cell membrane
Cytoplasm
Cell wall
Single circular strand of DNA
3
Q
What does nucleus contain?
A
The DNA in the form of chromosomes
4
Q
What does the cell membrane do?
A
Holds the cell together and controls what goes in and out
5
Q
What happens in the ribosomes?
A
Proteins are synthesised
6
Q
What’s cytoplasm?
A
A gel like substance where most of the cells chemical reactions happen
7
Q
What happens in mitochondria?
A
Respiration - provides energy for cell processes
Many found in liver cells (carry out energy demanding metabolic reactions)
and muscle cells (need energy to contract)
8
Q
What is the cell wall?
A
Made of cellulose and supports the cell shape
9
Q
Where does photosynthesis happen in the cell?
A
In the chloroplasts
10
Q
What is the vacuole?
A
Relatively large structure such as containing sap (a weak solution of sugar and salts)
11
Q
What is the structure of DNA?
A
Double helix
Each strand is made up of small groups of nucleotides
Each nucleotide contains a small molecule called a base
Each base forms cross links to an opposite base holding the strands tightly wound together
12
Q
What are the four different bases and what are their pairing?
A
A C T G
A-T
C-G
Complementary base pairing
13
Q
What did Watson and crick discover?
A
First to build a model of DNA a 1953
DNA structure
14
Q
What are the stages of DNA replication?
A
Double helix unzips to form two strands
New free floating nucleotides join on using complementary base pairing making an exact copy on each strand
15
Q
What controls the production of proteins in a cell?
A
DNA
The section that codes for a particular protein is a gene
16
Q
What are proteins made up of?
A
Chains of amino acids
17
Q
What’s different about different proteins?
A
Each has a specific number and order of amino acids giving each a different shape to do different functions
18
Q
How does a gene code for protein?
A
Order of the bases in a gene decides the order of amino acids in protein
Each amino acid is coded for by three bases
19
Q
How are proteins made?
A
mRNA carries the DNA code to the ribosomes (by copying it from the DNA) to make proteins
20
Q
How does DNA control a cell?
A
Decides what kind and how many proteins are made
Some genes are switched off
E.g in muscle cell only muscle cell proteins are switched on
21
Q
What are the four kinds of proteins?
A
Enzymes
Carrier molecules
Hormones
Structural proteins
22
Q
What 5 cell structures are found in an animal cell?
A
Nucleus Cell membrane Ribosome Cytoplasm Mitochondria
23
Q
What do carrier molecules do?
A
Transport smaller molecules e.g haemoglobin binds to oxygen molecules and transports them around the body
24
Q
What do hormones do?
A
Carry messages around the body
25
What are structural proteins?
Physically strong
| E.g. Collagen strengthens connective tissues
26
What do enzymes do?
Control cell reactions
27
What usually makes a reaction happen faster?
By raising the temperature
28
What are enzymes and why does our body produce them?
Biological catalysts
| Speeds up the reaction without hearing it up which damaged the cells
29
What's special about different enzymes?
Every different biological reaction has its own enzyme specifically designed for it
Every enzyme is codes for by a different gene
Each has a unique shape
30
What is a substrate?
The molecule changed in a reaction
31
What is an active site on an enzyme?
The part where it joins on to the substrate to catalyse the reaction
32
What's special about enzymes?
They have a high specificity for their substrate (only work for one substrate)
33
Why are enzymes so specific?
The substrate has to match the shape of the enzymes active site if it doesn't fit it won't be catalysed
"Lock and key" mechanism
34
Why does a higher temperature increase the rate of reaction?
More heat = more energy for the enzymes and substrate to move about and collide with each other - higher collision rate
35
What happens to enzymes if a reaction is too hot?
Some of the bonds holding the enzyme together will break so it will lose its shape - active site won't fit substrate - can't function
It is denatured
36
What does an enzymes optimum temperature mean and what is the right temperature for human enzymes?
It's the temperature that the reaction goes the fastest at
| 37 degrees C
37
What happens to enzymes if the pH is too high or low?
Interferes with bonds , enzyme loses shape - denatured
| All enzymes have an optimum pH
38
What's a Q10 value?
Shows how much the rate changes when the temperature is raised by 10 degrees
39
How do you calculate the Q10 value?
Rate at higher temperature
--------------------------------
Rate at lower temperature
40
What does it mean if the Q10 value is 2?
The rate doubles
| If it's three it trebles ectr....
41
What is a gene mutation and what can it cause?
Change in the DNA base sequence
It could stop the production of the protein the gene normally codes for - or a different protein could be produced instead
42
How can mutations be harmful?
Producing the wrong protein or none at all can be disastrous - especially if the protein is an important enzyme
If it occurs in reproductive cells the offspring might develop abnormally or die
If it occurs in body cells they could multiply uncontrollably and invade other parts of the body - cancer
43
How can mutations be beneficial?
The different protein produced could be an improvement on the old one
Gives them a survival advantage , gets passed on to next generation and becomes common - natural selection
44
What two things increase the chance of mutations occurring?
```
Ionising radiation (UV light and X-Rays and from radioactive sources) - greater the dose the greater the chance of mutation
Certain chemicals called mutagens (if the mutagens produce cancer they are called carcinogens)
```
45
What are 3 advantages of being multicellular?
You can be bigger - therefore can travel further, get nutrients in variety of ways, less things can eat or kill you
Cell differentiation - cells can be specifically adapted for their job
More complex - specialised organs, different shapes and behaviour a specific adaptations to your environment
46
What are the disadvantages to being multicellular?
Need specialised organ systems e.g.
Nervous system - cell communication
Circulatory system- supply nutrients
Respiratory system- exchange substances with environment
47
What is mitosis?
It's when a cell reproduces itself by splitting to produce two identical offspring
48
When is mitosis used in the body?
For growth
Replace worn out cells
Repair tissues
49
What are the 5 stages of mitosis?
DNA in cell is replicated
DNA coils into double armed chromosomes
Chromosomes line up in middle of cell then divide as cell fibres pull them apart - arms split and get pulled to opposite poles of the cell
Membranes form around each one armed cluster
Cytoplasm divides creating two new cells genetically identical
50
What's different about the arms in a double armed chromosome?
NOTHING!!! Lol trick question!!
| The left arm has exactly the same DNA as the right arm
51
What does diploid mean and give an example of a diploid cell
Each cell has two copies of each chromosome in its nucleus
| Body cells
52
What does haploid mean and give an example of a haploid cell
Cells only have one copy of each chromosome
| Gametes
53
What's the main difference between meiosis and mitosis?
Meiosis has two divisions whereas mitosis only has one
| Mitosis produces genetically identical cells
54
What are the four stages of meiosis?
DNA replicates coils into chromosomes and lines up in pairs
First division and the pairs are split in each new cell there are no pairs at all (still double armed chromosomes)
Second division and the arms at split creating four new cells each genetically different with half the amount of chromosomes needed
55
What is it called when male and female gametes combine to form a diploid cell at fertilisation?
A zygote - inherits chromosomes from two parents producing genetic variation
56
Name 3 ways that sperm cells are adapted for their function
The small and have long tails for swimming
Lots of mitochondria to provide the energy for swimming
Have an acrosome in the head to release enzymes that digest their way through the membrane of the egg cell
57
What are two differences between the way that plants and animals grow?
Animals grow until they reach a finite size but plants grow continuously
In animals growth happens by cell division but in plants it happens by cell elongation (some growth by cell division happens in meristems (tips of roots and shoots))
58
What is differentiation?
The process by which a cell changes to become specialised for its job
59
What is the difference between plant and animal cells as far as differentiation is concerned?
In most animal cells the ability to differentiate is lost at an early stage
In plant cells they don't ever lose the ability to differentiate
60
What are the cells in your body that are undifferentiated called?
Stem cells
61
Where are stem cells found?
In human embryos
| In bone marrow
62
What's the disadvantage of bone marrow stem cells compared to embryo stem cells?
Bone marrow stem cells can't turn into any cell only certain ones - aren't as versatile as embryo ones which can turn into any cell that's found in a human body
63
Give an example of how medicine already uses stem cells to cure disease
People with blood disorders (leukaemia and sickle cell anaemia) can be cured by bone marrow transplants
- bone marrow contain adult stem cells which can turn into new blood cells to replace the faulty ones
64
What is stem cell therapy?
Where scientists extract stem cells from embryos and use them to grow tissues to treat conditions such as:
Nerve cells to cure brain damage and spinal injuries
Skin cells for skin grafts
65
Why are some people against stem cell research?
Human embryos are potential human life
66
What are the arguments for stem cell research?
Citing patients who exist and are already suffering are more important than embryos
The embryos used are usually unwanted ones that would just be destroyed anyway
67
What are the three methods for measuring growth?
Measuring length
Weighing the wet mass
Weighing the dry mass
68
What's an advantage and a disadvantage of measuring the length to determine growth?
Easy to measure
| Doesn't tell you about the changes in width, diameter, no of branches....
69
What's an advantage and disadvantage of weighing wet mass to determine growth?
Easy to measure
| Very changeable - if it's rained plant is heavier , if eaten animal is heavier
70
Name an advantage and disadvantage of using dry mass to determine growth
Not affected by the amount of water in a plant or how much the animal has eaten and tells you the size of the whole organism
Have to dry out the organism to measure it which kills it
71
What are the five phases of human life?
```
Infancy - rapid growth
Childhood - steady growth
Adolescence - rapid growth
Maturity/adulthood - growth stops
Old age - between 65 and death
```
72
When are the two main phases of rapid growing for a human?
Just after birth (infancy) and during adolescence
73
Why do certain parts of the body grow faster or slower than others? - give example
When baby growing in womb the brain grows fastest giving them a big survival advantage
74
What is respiration?
The process of releasing energy from glucose
75
What happens to the energy made from respiration and why does this happen?
Used to make ATP - energy source for many cell processes and transports energy to where it's needs in the cell
The energy from respiration can't be used directly by cells
76
What is respiration controlled by and what does this mean?
Enzymes
| Means that the rate of reaction is affected by both temperature and pH
77
What are two types of respiration?
Aerobic respiration
| Anaerobic respiration
78
When does aerobic respiration happen?
When there's plenty of oxygen available
79
Why is aerobic respiration good?
It's the most efficient way to release energy from glucose
| The type you use all the time
80
What's the word equation for aerobic respiration?
Glucose + oxygen -> carbon dioxide +
| Water
81
What is the symbol equation for aerobic respiration?
C6-H12-O6 + 6O2 -> 6CO2 + 6H2O
82
What happens when the rate of aerobic respiration increases?
Both oxygen consumption and carbon dioxide production increase
83
What can be used to estimate metabolic rate?
Rate of oxygen consumption
84
What is anaerobic respiration?
Where you respire without using oxygen
85
When would you use anaerobic respiration and why?
When doing vigorous exercise your body can't supply enough oxygen to your muscles for aerobic respiration to happen so they respire anaerobically
86
What's the downside to anaerobic respiration?
Not the best way to convert glucose - releases less energy per glucose molecule than aerobic
Glucose only partially broken down so lactic acid is produced - build up is painful
87
What's the word equation for anaerobic respiration?
Glucose -> lactic acid + energy
88
What's the advantage of anaerobic respiration?
You can keep on using your muscles
89
What happens after you resort to anaerobic respiration?
You'll have an oxygen debt - you need extra oxygen to break down the lactic acid
Keep breathing hard for a while
Lactic acid has to be carried to liver to breakdown so heart rate is high
90
What is the respiratory quotient?
It can tell you whether someone is respiring aerobically or anaerobically
91
What's is the formula for calculating someone's respiratory quotient?
Amount of CO2 produced
----------------------------------
Amount of O2 used
92
How do you tell if the RQ value is aerobic or anaerobic?
Between 0.7 and 1 and its aerobic
| Greater than 1 and its anaerobic
93
What is plasma?
A pale yellow liquid which carries just about everything that needs to be transported around your body
94
What 7 things do plasma carry?
Red blood cells, white blood cells and platelets
Water
Digested food products (glucose and amino acids)
Carbon dioxide
Urea
Hormones
Antibodies
95
What do red blood cells do?
Transport oxygen from the lungs to all the cells in the body
96
Name 4 ways the red blood cell is adapted to its job
Small and have a bioncave shape so they have a large surface area to volume ratio to carry lots of oxygen
Contain haemoglobin
Don't have a nucleus - frees up space for more haemoglobin
Very flexible - easily pass through tiny capillaries
97
What are the three blood cells and what are their functions?
Arteries - carry blood away from the heart
Capillaries - exchange materials between tissues (supply food and oxygen and take away waste)
Veins - carry blood to the heart
98
What are the features of an artery?
Artery walls strong and elastic because it carries blood under high pressure
Walls contain thick layers of muscle for strength
Walls thick compared to the lumen
99
What are the features of capillaries?
Really tiny
Carry blood really close to every cell in the body
Permeable walls so things can diffuse through them
Walls only one cell thick increasing rate of diffusion
100
What are the features of a vein?
Big lumen to help blood flow
Have valves to keep the blood flowing in the right direction
Thinner walls than artery because blood flowing at low pressure
101
Describe our double circulatory system
First system connects heart to lungs
| Second system connects heart to rest of the body
102
What are the advantages of having a double circulatory system?
Returning blood to heart after lungs means it can be lumped around the body at higher pressure increasing blood flow meaning more oxygen is delivered to the cells faster - important for maintaining body temperature
103
What are the two sections in the right side of the heart called?
Right atrium and right ventricle
104
What are the names of the vein and artery that are connected to the right side of the heart?
Vein- vena cava
| Artery - pulmonary artery
105
What are the two valves in the right side of the heart called?
Tricuspid valve and semilunar valve
106
What is the name of the vein and the artery that is connected to the left side of the heart?
Vein - pulmonary vein
| Artery - aorta
107
What are the names of the two valves in the left side of the heart?
Bicuspid and semilunar valves
108
What is the names of the two chambers on the left side of the heart?
Left atrium
| Left ventricle
109
What kind of blood does the right side of the heart pump?
Deoxygenated
110
What kind of blood does the left side of the heart pump?
Oxygenated
111
What chamber of the heart does blood enter first?
Atrium
112
What's different about the left ventricle compared to the right?
Much thicker wall - needs more muscle because it has to pump blood around the whole body
113
What do the valves do?
Prevent the back flow of blood
114
What is selective breeding?
When humans artificially select the plants or animals we are going to breed based on the genes they carry which give the the best features
115
Name 3 features that people selectively breed for
Maximum yield of meat, milk, grain...
Good health and disease resistance
Temperament, speed, attractiveness....
116
What are the four stages of selective breeding?
Select the animals with best characteristics
Breed them with each other
Select the best offspring and breed together
Continue over several generations and desirable trait gets stronger
117
What are the problems with selective breeding?
Reduced the gene pool
Inbreeding - more chance of developing harmful genetic disorders
Not much variation so disease can wipe out whole stock
118
What is the advantage of genetic engineering?
You can produce organisms with new and useful features very quickly
119
What is the risk of genetic engineering?
That the inserted gene has harmful effects (making unstoppable pathogens ectr)
120
What are the 4 stages of genetic engineering?
The gene which contains the desirable characteristic is created
It's cut from the DNA using enzymes and isolated
Inserted into DNA of another organism (bacteria)
Organism replicates creating loads of the useful gene
121
Name three examples of genetic engineering
Beta carotene gene taken from carrots and put into rice plants (beta carotene makes vitamin A) - in poor parts of world they rely heavily on rice but have Vitamin A deficiency
Human insulin production in bacteria
Herbicide, frost damage and disease resistance inserted into crops
122
List 3 moral or ethical issues to do with genetic engineering
it's wrong to genetically engineer organisms (animals) solely for human benefit
It won't stop at plants and animals - genetically engineered babies
Evolutionary consequences unknown - irresponsible to carry on when we don't know what impact it will have
123
What is gene therapy?
Altering a persons genes in an attempt to cure genetic disorders
124
What are the two types of gene therapy?
First - changing genes in body cells (could still pass disease on to kids)
Second - changing the genes in gametes so it won't be passed on but every cell in the child's body would be affected by the gene therapy
125
Why is the gene therapy involving gametes controversial?
Illegal in humans
Might cause a whole host of new problems
May lead to creation of "designer babies"
126
What are clones?
Genetically identical organisms
127
What are the 4 stages of cloning?
Nucleus of egg cell removed (egg cell has no genetic information)
Diploid nucleus from a body cell from the animal being cloned inserted (contains the new genetic information)
Egg cell given an electric shock to start the dividing by mitosis (as if normally fertilised)
Dividing cell implanted into surrogate mother and clone is born
128
What are the benefits of cloning?
Mass produce animals with desirable characteristics
- pig organs cloned so constant supply (for transplant into humans)
Human embryos made by cloning patient body cells so the stem cells could be extracted and used in stem ell therapy - reduces risk of rejection
129
What are the risks of cloning?
Cloned animals might not be as healthy as normal ones
| May have consequences we don't know about
130
What are the ethical issues with cloning humans?
Lots of surrogate pregnancies with high levels of miscarriage and stillbirth
Clones of other mammals have been unhealthy and died prematurely - humans could too
Clone might be psychologically damaged by knowledge it's a clone
131
Why is it easier to clone plants that animals?
Because plant cells keep their ability to differentiate
132
What are the 4 stages of cloning a plant?
Choose a plant with desirable characteristics
Remove several small pieces of tissue - best results from a fast growing root or shoot
Grow tissue in a growth medium containing nutrients and growth hormones - under aseptic conditions
When roots and shoots produced move to potting compost to carry on growing
133
What are the pros and cons of the commercial use of cloned plants?
Only get good plants with the desirable characteristics
Can mass produce plants that are hard to grow from seeds
Lack of genetic variation
A disease can kill them all off at once
