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Biology > B3- Living and Growing > Flashcards

B3- Living and Growing Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is mitochondria?

A

Structures in a cell where respiration takes place

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2
Q

What does the number of mitochondria in the cytoplasm depend on?

A

The activity of the cell

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3
Q

Which cells have large numbers of mitochondria?

A

Liver or muscle cells because the liver carries out many functions and muscle cells need to contract

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4
Q

What are ribosomes?

A

Structures in a cell where protein synthesis takes place

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5
Q

What does the nucleus contain?

A

Genes

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6
Q

What is a gene?

A

Section of DNA that codes for a particular characteristic

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7
Q

What is the structure of DNA?

A
  • two strands coiled to form a double helix
  • each strand contains chemicals called bases
  • bases cross links between strands
  • each gene contains a different sequence of bases
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8
Q

Where are proteins made?

A

Cytoplasm

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9
Q

How does DNA leave the nucleus?

A

DNA itself cannot leave the nucleus, so a copy of that gene needs to be made so it can leave the nucleus and carry the code to the cytoplasm

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10
Q

What are the 4 bases?

A

A, T, C, G

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11
Q

What is complementary base pairing?

A

The bases always pair the same way

A-T and G-C

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12
Q

What does the DNA base code control?

A

Which protein is made

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13
Q

How is an amino acid coded for?

A

By a sequence of three bases

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14
Q

What does the mRNA do?

A

messenger RNA carries the code needed to produce a protein from the DNA to the ribosomes

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15
Q

What did Watson and Crick do?

A
  • built a model of DNA using data from other scientists
  • photographs were taken using x-rays showing that DNA had two chains wound in a helix
  • data indicates that the bases occurred in pairs
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16
Q

When did Watson and Crick work out the structure of DNA?

A

1953

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17
Q

When did Watson and Crick win the Nobel Prize?

A

1962

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18
Q

Why was there a delay between Watson and Crick receiving the prize?

A

Other scietists needed to check the discovery was correct before giving them the prize

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19
Q

What are all proteins made of?

A

Long chians of amino acids joined together

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20
Q

What are the 4 types of protein functions?

A
  1. structural proteins used to build cells and tissues (e.g. collagen)
  2. hormones which carry messages to control a reaction (e.g. insulin)
  3. carrier proteins (e.g. haemoglobin)
  4. enzymes
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21
Q

Each protein has its own number and order of amino acids.

What does this mean?

A

Each protein molecule is a different shape and gives it a different function

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22
Q

Why are enzymes biological catalysts?

A

They speed up reactions in the body

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23
Q

What chemical reactions do enzymes catalyse?

A
  • respiration
  • photosynthesis
  • protein synthesis
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24
Q

What is the ‘lock and key mechanism’?

A
  • substrate molecule fits into active site of enzyme
  • forming an enzyme-substrate complex
  • releasing its products
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25
Q

What is specificity in enymes?

A

Each enzyme can only work on a particular substrate

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26
Q

What is the optimum?

A

Enzymes work best at a particular temperature and pH. Any change away from the optimum will slow down the reaction

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27
Q

How is enzyme activity affected by pH and temperature?

A
  • low temperatures, molecules are moving slowly so enzyme and substrate are less likely to collide
  • at very high or low pH values and high temperatures, enzyme active site changes shape (denatures) so substrate cannot fit and cannot react quickly
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28
Q

How do you work out the rate of reaction?

A

By calculating temperature coefficient, called Q10 for a 10ºC change in temperature

Q10= rate at higher temperature / rate at lower temperature

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29
Q

What are mutations?

A

DNA within cells have been altered

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30
Q

How might mutations occur?

A

Spontaneously but can be made to occur more often by radiation or chemicals

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31
Q

What can mutations cause?

A
  • production of different proteins
  • harmful, but may not have an effect
  • occasionally they might give the individual and advantage
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32
Q

What allows different cells to perform different functions?

A

Different genes are switched off in different cells

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33
Q

What do gene mutations do?

A

Alter or prevent the production of protein that is normally made because they change the base code of DNA, so change order of amino acids in the protein

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34
Q

Why is respiration important?

A

It releases energy from food and this energy is trapped in ATP, which can be used to provide energy for many different processes in living organisms

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35
Q

What is the aerobic respiration equation?

A

C6H12O6 + 6O2 → 6H2O + 6CO2

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36
Q

When does the body respire anaerobically?

A

Often during exercise, when the muscles do not receive sufficient oxygen

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37
Q

What is the word equation for anaerobic respiration?

A

glucose → lactic acid (+energy)

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38
Q

What are the disadvantages of anaerobic respiration?

A
  • lactic acid that is made builds up in muscles, causing pain and fatigue
  • anaerobic respiration releases much less energy per glucose molecule that aerobic respiration
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39
Q

What is oxygen debt?

A

The incomplete breakdown of glucose resulting in the build up of lactic acid

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40
Q

Why does breathing rate and heart rate stay high during recovery?

A
  • rapid blood flow can carry lactic acid away to the liver
  • extra oxygen can be supplied, enabling the liver to break down the lactic acid
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41
Q

What experiments can be used to measure the rate of respiration?

A
  1. measuring how much oxygen is used up - the faster it is consumed, the faster the respiration rate
  2. the rate at which carbon dioxide is made
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42
Q

How can you calculate respiratory quotient?

A

RQ = carbon dioxide produced / oxygen used

43
Q

What is the metabolic rate?

A

The sum of all the reactions that are occurring in the body. If metabolic rate is high, more oxygen is needed, as aerobic respiration is faster

44
Q

What can affect respiration rate?

A

Changes in temperature and pH because they affect enzymes, and respiration is controlled by enzymes

45
Q

What does multicellular mean?

A

Organisms made up of many specialised cells

46
Q

What are the advantages of being multicellular?

A
  • organism can become larger and more complex
  • different cells to take on different jobs

Cell differentiation

47
Q

What systems must a multicellular organism have?

A
  • allow communication between all cells in the body
  • supply all cells with enough nutrients
  • control exchanges with environment such as heat and gases
48
Q

What process produces new cells for growth?

A

Mitosis

49
Q

What are the products of mitosis?

A

Genetically identical cells

50
Q

What must happen before mitosis occurs?

A

DNA replication

51
Q

Why must DNA replication occur before cell division?

A

So that each cell produces still has two copies of each chromosome

52
Q

What are diploid cells?

A

Cells that have two copies of each chromosome

53
Q

What is the process of mitosis?

A
  1. cell resting
  2. each chromosome is copied, single strand forms double-stranded ‘X’ shape
  3. spindle forms, chromosomes arranged along equator
  4. chromosome single strands move to poles of cell
  5. two genetically identical cells are produced
54
Q

What is the process of DNA replication?

A
  1. two strands of DNA molecule ‘unzipping’ to form single strands
  2. new double strands forming by DNA bases lining up in complementary base pairings
55
Q

What process produces gametes?

A

Meiosis

56
Q

What are haploid cells?

A

Cells that contain only one chromosome from each pair

57
Q

What produces genetic variation?

A

The zygote gets one copy of a gene from one parent and another copy from the other parent

58
Q

How is the sperm structure adapted to its function?

A
  • many mitochondria to provide energy for swimming to the egg
  • an acrosome that releases enzymes to digest the egg membrane
59
Q

What is the process of meiosis?

A

diploid cells- the single strands are copied to make X shaped chromosomes

  1. chromosomes pair up
  2. one from each pair moves to each pole
  3. strands of each chromosome are pulled apart to opposite poles
  4. four new haploid cells form, all genetically different from each other
60
Q

What is the liquid part of the blood called?

A

Plasma

61
Q

What does plasma carry around the body?

A
  • dissolved substances from tissue to lungs
  • carbon dioxide
  • hormones from glands to their target cells
  • plasma proteins such as antibodies
  • waste substances such as urea
62
Q

How are red blood cells adapted to their function?

A
  • very small so they can pass through blood vessels
  • shaped like biconcave discs (large surface area to exchange oxygen quicker)
  • contain haemoglobin to combine with oxygen (makes them appear red)
  • don’t have a nucleus so more haemoglobin can fit
63
Q

What is formed when haemoglobin reacts with oxygen?

A

Oxyhaemoglobin

64
Q

What happens when oxyhaemoglobin reaches the tissues?

A

Oxygen is released

(the reaction is reversible)

65
Q

What does the biconcave shape of red blood cells provide?

A

Larger surface area to volume ratio to exchange oxygen more quickly

66
Q

What are the different types of blood vessels?

A
  • arteries
  • veins
  • capillaries
67
Q

What jobs do the blood vessels have?

A
  • arteries transport blood away from the heart to the tissues
  • veins transport blood back to the heart from tissues
  • capillaries link arteries to veins and allow materials to pass between blood and tissues
68
Q

How are arteries adapted?

A

Thick muscular and elastic wall to resist high pressure

69
Q

How are veins adapted?

A

Have large lumen and valves to try keep blood moving back to the heart because the pressure is low

70
Q

How are capillaries adapted?

A

Permeable walls so substances can be transferred between blood and tissues

71
Q

How does the heart circulate blood?

A
  • atria receive blood from veins
  • ventricles pump blood out into arteries
  • valves prevent backflow of blood
  • pulmonary vein and vena cava are the main veins carrying blood back to heart
  • aorta and pulmonary artery carry blood away from heart
72
Q

Why does the left ventricle have a thicker muscle wall?

A

It has to pump blood all around the body rather than just to the lungs

73
Q

What is a double circulatory system?

A

Where blood is pumped to the lungs then returned to the heart before being pumped round the body

74
Q

What are the advantages of a double circulatory system?

A

Blood is at a higher pressure so flows to the tissues at a faster rate

75
Q

How are bacterial cells different from plant and animal cells?

A

They lack a ‘true’ nucleus, mitochondria and chloroplasts

76
Q

Where is DNA found in a bacterial cell?

A

In the cytoplasm as a single circular strand or chromosome

77
Q

What does the growth curve diagram show?

A

There are two phases which involve rapid growth: one after birth and in adolescence

78
Q

What is the best measure of growth?

A

Dry mass

79
Q

What is good and bad about measuring growth by length?

A

Easy to do but measures growth in one direction only

80
Q

Why is measuring wet mass hard?

A

Difficult for some organisms such as trees, but easier for animals. However, water content of organisms can vary with time

81
Q

What is good and bad about measuring dry mass?

A

It involves killing the organism and driving off water, but it does measure the true growth of the whole organism

82
Q

Why does different parts of the organism grow at different rates?

A

Different parts of the organism may be needed at different times during the life of the organism

83
Q

What are stem cells?

A

Unspecialised body cells (found in bone marrow) that can develop into other, specialised cells that the body needs e.g. blood cells

84
Q

Where can you obtain stem cells?

A

From embryos

85
Q

What can stem cells be used for?

A

Treating some medical conditions

86
Q

What are the issues with stem cell research?

A

It is wrong because embryos are destroyed

It is acceptable as it can treat life-threatening diseases

87
Q

Why are adult stem cells not used?

A

They are unspecialised cells that can develop into many (but not all) types of cells and are not very easy to find

88
Q

What are the differences between plant and animal growth?

A
  • animals tend to grow to a certain size, but plants can carry on growing
  • plant cell division only happens in meristems (tips of roots and shoots)
  • main way plants gain height is by cells enlarging rather than dividing
  • plants keep ability to differentiate, but most animal cells lose it at an early stage
89
Q

What are problems with selective breeding?

A
  • may lead to interbreeding (two closely related individuals mate)
  • health problems within species
90
Q

What can interbreeding lead to?

A

Reduce the variety of alleles in the population (gene pool), which can lead to:

  • increased risk of harmful recessive characteristics showing up in offspring
  • reduction in variation, so that populations cannot adapt to change so easily
91
Q

What are the risks and advantages of genetic engineering?

A

Advantage

  • organisms with desired features can be produced quickly

Risk

  • inserted genes may have unexpected harmful side effects
92
Q

What are examples of organisms made using genetic engineering?

A
  • rice containing beta-carotene to increase the amount of vitamin A
  • genetically engineered bacteria to produce human insulin
  • crop plants made resistant to herbicides, frost, or diseases
93
Q

What are the ethical issues with genetic engineering?

A
  • worry about the possible long term effects (damage to natural ecosystems)
  • it is morally wrong, whatever the intended benefits
94
Q

What steps are taken for genetic engineering?

A
  1. desired characteristics are selected
  2. genes responsible are identified and removed (isolation)
  3. genes inserted into other organisms
  4. organisms allowed to reproduce (replication)
95
Q

What is gene therapy?

A

Process of using genetic engineering to change a person’s genes and cure certain disorders

96
Q

Why is changing genes in gametes controversial?

A

It is difficult to decide which parents should be allowed to change as it could lead to ‘designer babies’

97
Q

How does cloning using nuclear transfer work?

A

Involves removing the nucleus from a body cell and placing it into an egg cell that has had its nucleus removed

98
Q

Why would animals be cloned?

A
  • mass-produce animals with desirable characteristics
  • produce animals that have been genetically engineered to provide human products
  • produce human embryos for stem cell therapy
99
Q

What are the dilemmas with human cloning?

A

People see it as wrong to clone people as they will not be ‘true individuals’

100
Q

What steps where involved when Dolly the sheep was cloned?

A
  1. donor egg had its nucleus removed
  2. egg cell nucleus replaced with nucleus from udder cell (body cell)
  3. egg cell given an electric shock to divide
  4. embryo implanted into a surrogate mother sheep
  5. embryo grew into a clone of sheep from which the udder cell came
101
Q

What are the advantages and disadvantages of plant cloning?

A

Advantage

  • growers can be sure of characteristics of each plant
  • mass-produce plants that may be difficult to grow from seed

Disadvantage

  • if plants become susceptible to disease/change in environment, then all plants are affected
  • lack of genetic variation in plants
102
Q

What are the steps of tissue culture cloning?

A
  1. plant is selected that has certain characteristics
  2. large number of small pieces of tissue are cut from plant
  3. small pieces of tissue are grown in test tubes or dishes containing a growth medium
  4. aseptic technique is used at all stages to stop any microbes infecting plants
103
Q

Why are plant cells easier to clone?

A

Plant cells retain the ability to differentiate, but animal cells lose this ability at an early stage

Biology (6 decks)

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