GCSE Biology B3

  • Created by: Ruqayya11
  • Created on: 15-04-17 14:06
What do mitochondria in the cytoplasm of a cell depend on?
They depend on the activity of the cell. This is because respiration occurs in mitochondria
1 of 85
Why do cells such a liver and muscle cells have large numbers of mitochondria?
This is because the liver carries out many functions and muscle cells need to contract. Both types of cells therefore need lots of energy
2 of 85
Where are ribosomes found, and what is its function?
Ribosomes are found in the cytoplasm and are the site of protein synthesis
3 of 85
What does a nucleus contain?
It contains genes. Each gene is a section of a chromosome made of DNA and it codes for a particular protein
4 of 85
What is DNA made of?
DNA is made of two strands coiled to form a double helix, each strand containing chemicals called bases. Each gene contains a different sequence of bases
5 of 85
How does DNA reach the cytoplasm?
Protein is made in the cytoplasm but DNA cannot leave the nucleus. This means that a copy of the gene needs to be made that can leave the nucleus and carry the code to the cytoplasm
6 of 85
What are the 4 bases in DNA?
A, T, C, G. The cross links holding the two strand together are always between the same bases, A-T and C-G. This is complementary base pairing
7 of 85
What does the DNA base code control?
It controls which protein is made. This is because the base sequence in the DNA codes for the amino acid sequence in the protein. Each amino acid is coded for by a sequence of three bases
8 of 85
What is the code needed to produce a protein?
The code is carried from the DNA to the ribosomes by a molecule called Messenger RNA
9 of 85
Explain how DNA replicates?
The two strands of the DNA molecule unzip to form single strands. New double strands are formed by DNA bases lining up in complementary pairings
10 of 85
What did Watson and Crick use to aid them in building the structure of DNA?
Photographs taken using x-rays which showed that DNA had two chains wound in a helix. Data indicating that the bases occurred in pairs
11 of 85
What are proteins made of?
Long chains of amino acids joined together
12 of 85
What are the different functions of proteins?
Structural proteins used to build cells and tissues- collagen. Hormones, which carry messages to control a reaction. Carrier proteins- haemoglobin, which carries oxygen. Enzymes
13 of 85
Explain what is meant by protein synthesis?
This is the process of cells generating new protein
14 of 85
What are enzymes?
Enzymes speed up reactions in the body and so are called biological catalysts. They catalyse chemical reactions occurring in respiration, photosynthesis and protein synthesis of living cells
15 of 85
Why are enzymes described as working according to the 'lock and key mechanism'?
The substrate molecule fits into the active site of the enzyme like a lock into a key. It also explains why each enzyme can only work on a particular substrate. This is called specificity and it happens because the substrate has to be the right shape
16 of 85
Explain how enzyme activity is affected by low temperatures?
At low temperatures molecules are moving more slowly and so the enzyme and substrate are less likely to collide
17 of 85
Explain how enzyme activity is affected by high temperatures and low or high pH?
At very high or low pH values or high temperatures the enzyme active site changes shape. This is called denaturing. The substrate cannot fit, so cannot react so quickly
18 of 85
Explain what is meant by a mutation?
A mutation is a change to the DNA base sequence
19 of 85
What results in mutations occurring more frequently?
They occur spontaneously but can me made to occur more often by radiation or chemicals
20 of 85
What happens when mutations occur?
This may lead to the production of different proteins. They can cause cells to keep on dividing. They can cause enzymes to stop functioning. They occasionally might give the individual an advantage
21 of 85
Why aren't all the same proteins made if every cell has the same genes?
This is because different genes are switched off in different cells. This allows different cells to perform different functions
22 of 85
Why do gene mutations alter or prevent the production of protein?
This is because they change the base code of DNA, and so change the order of amino acids in the protein
23 of 85
What is the function of ATP?
ATP traps the energy released by respiration, and using this energy for many different processes in living organisms
24 of 85
What is aerobic respiration?
Aerobic respiration involves the use of oxygen. C6H12O6 + 6O2 -> 6CO2 + 6H2O
25 of 85
Why do muscles start to use anaerobic respiration?
This is because during exercise, despite an increase in breathing rate and heart rate, the muscles do not receive enough oxygen
26 of 85
What is the word equation for anaerobic respiration?
Glucose -> lactic acid + energy
27 of 85
Identify the disadvantages of anaerobic respiration over aerobic?
The lactic acid that is produced, builds up in muscles causing pain and fatigue. Anaerobic respiration releases much less energy per glucose molecule than aerobic
28 of 85
Explain what is meany by the term oxygen debt?
The incomplete breakdown of glucose resulting in the build-up of lactic acid is called oxygen debt
29 of 85
During recovery, why do the breathing rate and heart rat stay high?
Rapid blood flow can carry lactic acid away to the liver. Also extra oxygen can be supplied, enabling the liver to break down the lactic acid
30 of 85
Explain the possible methods of measuring the rate of respiration?
The rate at which carbon dioxide is made, and measuring how much oxygen is used up- the faster it is consumed, the faster the respiration rate
31 of 85
Explain what is meant by the term metabolic rate?
The sum of all the reactions that are occurring in the body
32 of 85
Explain why changes in temperature and pH affect the rate of respiration?
This is because respiration in controlled by enzymes , and high temperatures will stop them from working
33 of 85
Identify the advantages of being multicellular?
It allows an organism to become larger and more complex. It also allows different cells to take on different jobs- cell differentation
34 of 85
What systems does an organism require when it becomes multicellular?
Systems that allow communication between all cells, that supply all the cells with nutrients, that control exchanges with the environment
35 of 85
Explain what mitosis is?
The process that produces new cells for growth. The cells that are made my mitosis are genetically identical
36 of 85
Explain why DNA replication must take place before the cells divide?
This is so that each cell produced still has two copies of each chromosome
37 of 85
Explain what is meant by diploid cells?
Having two copies of each chromosome
38 of 85
Stages of Mitosis- Prophase?
Each chromosome in the cell is copied, the single strand forms a double-stranded X
39 of 85
Stages of Mitosis- Metaphase?
Nucleus disappears and spindle forms. The chromosomes arrange along an equator
40 of 85
Stages of Mitosis- Anaphase?
Cell fibres pull, and chromosome single strands move to poles of cell
41 of 85
Stages of Mitosis- Telophase?
Membranes form around the separated chromosomes. Two genetically identical cells are produced
42 of 85
What is meiosis?
The type of cell division that produces gametes
43 of 85
Explain what is meant by a gamete being a haploid cell?
They contain only one chromosome from each pair. This means that the zygote gets one copy of a gene from one parent and another copy from the other parent- produces genetic variation
44 of 85
Stages of meiosis?
First the single strands are copied to make X-shaped chromosome and chromosomes with the same genes pair up
45 of 85
Stages of Meiosis- First division?
In the first division, one chromosome from each pair moves to opposite poles of the cell
46 of 85
Stages of Meiosis- Second division?
In the second division, the copies of each chromosome come apart and move to opposite poles of the cell
47 of 85
What substances does the plasma carry around the body?
Dissolved food substances such as glucose. Carbon dioxide from the tissues to the lungs. Hormones from the glands. Waste substances such as urea
48 of 85
How are red blood cells adapted to their function of carrying oxygen?
They are small so they can pass through capillaries. They are shaped like biconcave discs so they have a large surface area to exchange oxygen quicker. They contain haemoglobin to combine with oxygen. They don't have a nucleus-haemoglobin can fit
49 of 85
What does haemoglobin in red blood cells combine with?
It combines with oxygen, forming oxyhaemoglobin. This reaction is reversible: when the oxyhaemoglobin reaches the tissues, the oxygen is released
50 of 85
Identify the different types of blood vessels?
Arteries transport blood away from the heart to tissue. Veins transport the blood back to the heart. Capillaries link arteries to veins and allow materials to pass between blood and tissues
51 of 85
Explain the structure of arteries?
Arteries have a thick muscular and elastic wall to resist the high pressure
52 of 85
Explain the structure of veins?
Veins have large lumen and valves to try and keep the blood moving back to the heart because the pressure is too low
53 of 85
Explain the structure of capillaries?
Capillaries have permeable walls so substances can be transferred between the blood and the tissues
54 of 85
What is the role of the left and right atria?
Receiving blood from veins
55 of 85
What is the role of the left and right ventricles?
Pumping blood out into arteries
56 of 85
What is the role of the semilunar, tricuspid and bicuspid valves?
Preventing any backflow of blood
57 of 85
What is the role of the pulmonary vein and the vena cava?
The main veins carrying blood to the heart
58 of 85
What is the role of the aorta and pulmonary artery?
Carrying blood away from the heart
59 of 85
Why does the left ventricle have a thicker muscle wall than the right?
This is because it has to pump blood around the body rather than just to the lungs, which are close by
60 of 85
Explain what a double circulatory system is?
The blood is pumped to the lungs and returns to the heart to be pumped to the body. This means the blood is at a higher pressure and so flows to the tissues at a faster rate
61 of 85
How do bacterial cells differ from plant and animal cells?
They differ as they do not have mitochondria, chloroplasts and a nucleus
62 of 85
Where is DNA located in a bacterial cell?
As it does not have a nucleus, DNA is found in the cytoplasm as a single strand or chromosome
63 of 85
Identify the 5 main stages of growth?
Infancy, Childhood, Adolescence, Maturity, Old age
64 of 85
Why are stem cells described as undifferentiated?
They can develop into different types of cells
65 of 85
Where are stem cells obtained from?
They are obtained from embryos and can potentially be used to treat some medical conditions
66 of 85
What are the issues arising from stem cell research?
Human embryos are destroyed- and they can be considered human life.
67 of 85
Why do some people find it acceptable?
It can treat life-threatening diseases
68 of 85
What are the differences between plant and animal growth?
Animals tend to grow to a certain size but many plants carry on growing. Plant cell division only happens in areas called meristems. Plants gain height by cells enlarging rather than dividing. Plants keep the ability to differentiate, animals lose it
69 of 85
What are the problems with selective breeding programmes?
They may lead to inbreeding, where two closely related individuals mate, and this can cause health problems within the species
70 of 85
What can inbreeding lead to?
An increased risk of harmful recessive characteristics showing up in offspring. A reduction in variation, so that population cannot adapt to change so easily
71 of 85
Explain the advantages and disadvantages of Genetic Engineering?
A- organisms with desired features can be produced very quickly. D- there is a risk that the inserted genes may have harmful side effects
72 of 85
Examples of genetic engineering?
Genetically engineered bacteria have been made that produce human insulin. Crop plants have been made that are resistant to herbicides, frost damage or disease
73 of 85
Identify the ethical issues involved in genetic engineering?
Some people are worried about possible long-term side effects . Other people think that it is morally wrong, whatever the benefits
74 of 85
Identify the steps to carry out genetic engineering?
The desired characteristics are selected. The genes are responsible are identified and removed. The genes are inserted into other organisms. The organisms are allowed to reproduce
75 of 85
Explain what is meant by gene therapy?
The process of using genetic engineering to change a person's gene and cure certain disorders. It could involve body cells or gametes
76 of 85
Why is changing genes in gametes more controversial?
This is because it is sometimes difficult to decide which genes parents should be allowed to change- lead to designer babies
77 of 85
Why are animals cloned?
To mass produce animals with desirable characteristics. To produce animals that have been genetically engineered to provide human products. To produce human embryos to supply stem cells for therapy
78 of 85
Explain the process of nuclear transfer?
This involves removing the nucleus from a body cell and placing it into an egg cell that has had its nucleus removed
79 of 85
Identify the steps involved in nuclear transfer?
The donor egg cell has its nucleus removed. The egg cell nucleus was replaced with the nucleus from an udder cell. The egg cell was then given an electric shock to make it divide. The embryo is implanted into a surrogate mother
80 of 85
Explain the benefits of cloning?
Supplying replacement organs for humans, gain a healthier amount of animals to eat, stop extinction
81 of 85
Advantages of producing cloned plants?
Growers can be sure of the characteristics of each plant since all the plants will be genetically identical. It is also possible to mass-produce plants that may be difficult to grow from seed
82 of 85
Disadvantages of producing cloned plants?
If the plants become sustainable to disease or to change in the environmental conditions, then all the plants will be affected. There is a lack of genetic variation in the plants
83 of 85
Identify the steps to carry out tissue culture?
A plant is selected that has certain characteristics. A large number of small pieces of tissue are cut from the plant. The small pieces of tissue are grown in test tubes containing a growth medium. Aseptic technique is used at all stages
84 of 85
Explain why cloning plants is easier than cloning animals?
This is because many plant cells retain the ability to differentiate. Animal cells, however, lose this ability at an early stage
85 of 85

Other cards in this set

Card 2


Why do cells such a liver and muscle cells have large numbers of mitochondria?


This is because the liver carries out many functions and muscle cells need to contract. Both types of cells therefore need lots of energy

Card 3


Where are ribosomes found, and what is its function?


Preview of the front of card 3

Card 4


What does a nucleus contain?


Preview of the front of card 4

Card 5


What is DNA made of?


Preview of the front of card 5
View more cards


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Living and Growing resources »