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Biology extension edexcel > B3.1 Control systems > Flashcards

B3.1 Control systems Flashcards

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1
Q

What is a circadian rhythm?

A

A biological rhythm that happens over one day

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2
Q

What is the biological clock?

A

A timing mechanism in the body that helps to control various rhythms, like sleeping and waking

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3
Q

What does melatonin do?

A

Makes people sleepy

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4
Q

Why does the biological clock need regular exposure to day and night?

A

To keep it in sync with the 24 hour cycle

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5
Q

Why do flowers open during the daytime?

A

Because it means that insects can pollinate them

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6
Q

Why do flowers only produce nectar during the day?

A

Because that is when insects are likely to visit them

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7
Q

What is a response to changing day length called?

A

Photoperiodism

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8
Q

What is left after a plant dies during winter?

A

Seeds

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9
Q

What do seeds do as they days get longer during spring?

A

Germinate

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10
Q

What happens to the growth of plants as days get longer?

A

It gets faster

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11
Q

What are the poisonous chemicals that lupin produces called?

A

Alkaloids

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12
Q

Why does lupin produce alkaloids?

A

To be poisonous to insect pests and large herbivores that might want to eat them

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13
Q

What is a pathogen?

A

An organism that causes disease

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14
Q

How does potato blight kill potatoes?

A

It kills their leaves so they are no longer able to photosynthesise and so don’t have any energy for respiration and die

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15
Q

What do some potatoes do in response to potato blight?

A

They produce chemicals to kill it

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16
Q

What effect does a pathogen destroying or damaging a crop have on humans?

A

The food supply is at risk and so there could be a famine

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17
Q

What is digoxin?

A

A chemical found in fox gloves

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18
Q

What medical use can digoxin be used for?

A

It can be used to treat heart disorders when used in small doses

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19
Q

What are many plant poisons commonly used for?

A

Making medicinal drugs

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20
Q

What is quinine used for?

A

Treating the symptoms of malaria

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21
Q

Where is quinine found?

A

Cinchona trees

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22
Q

What is aspirin produced from?

A

Willow trees

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23
Q

What is aspirin used for?

A

Treating symptoms of disease such as pain or fever

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24
Q

What parts of a potato are poisonous?

A
  • the leaves because that’s where poisonous alkaloids are produced
  • the tubers if they have been exposed to light and gone green
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25
Q

Who proved that micro organisms were responsible for some diseases and foods going off?

A

Louis Pasteur

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26
Q

What did Louis Pasteur suggest people do to stop diseases and prevent food from going off?

A

Keep micro organisms away from people and food

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27
Q

What are aseptic techniques?

A

The methods used to keep things free from living micro organisms

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28
Q

What is pasteurisation?

A

The process of briefly heating foods (such as milk) before storing them in order to kill bacteria

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29
Q

What experiment did Louis Pasteur do to prove that micro organisms caused disease and food to go off?

A
  • he put broth in one straight necked flask and one swan necked flask after boiling both for one hour
  • the broth in the straight necked flask went off after four days because the bacteria had easy access to the broth
  • the broth in the swan necked flask stayed fresh after four days because all the bacteria collected in the swan neck
  • this showed that when bacteria had access to the broth it caused it to go off
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30
Q

What three things do bacteria need to grow quickly?

A

Food, oxygen and warmth

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31
Q

What is exponential growth?

A

When the growth rate of a population is proportional the population’s current value

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32
Q

What could happen if you drink milk with high levels of bacteria?

A

It cause infections of the gut such as food poisoning

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33
Q

What is a way of measuring how much bacteria there is in a sample?

A

Using resazurin dye, as it shows how quickly oxygen is used up. So if there are more bacteria they respire more, so the resazurin is used up more quickly

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34
Q

What are the different colours resazurin can be?

A
  • blue when there is plenty of oxygen

- pink and eventually colourless when oxygen levels fall

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35
Q

Who created the first vaccine?

A

Edward Jenner

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36
Q

How did Edward Jenner discover vaccines?

A

He noticed that milk maids didn’t seem to get smallpox,and from this he came to the conclusion that getting cowpox might prevent a person from getting smallpox. To test this he took the pus from a cowpox blister and rubbed it into the skin of a boy called James Phipps, who only got a mild fever. After that he did the same with a smallpox blister, but James didn’t get sick as the cowpox vaccine had made him immune

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37
Q

What are antigens?

A

Proteins that the immune system recognises as foreign found on the outer surfaces of viruses and cells

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38
Q

How does the immune system destroy foreign viruses and cells?

A

By recognising foreign antigens and getting antibodies to stick to the pathogen antigens

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39
Q

What does a vaccine contain?

A

Harmless version of the pathogen a person is vaccinating against

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40
Q

What type of white blood cell respond to a vaccine?

A

Lymphocytes

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41
Q

What are memory lymphocytes?

A

Lymphocytes left over from a previous attack on the immune system so that a pathogen can be killed more quickly in case it comes back

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42
Q

What is the immune response?

A

The way the body responds to infection

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43
Q

What is infection?

A

The process of an illness being caused by the entry of a pathogen into the body

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44
Q

What is immunisation?

A

Making someone immune to a disease

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45
Q

How does a vaccine make you immune?

A
  • a weakened pathogen is injected into the body. It has antigens on its surface
  • a lymphocyte with an antibody that perfectly fits the antigen is activated
  • this lymphocyte divides over and over to produce clones of identical lymphocytes
  • these lymphocytes do the following things: some secret large amounts of antibodies, some stick to the antigens and destroy the pathogen and some remain in the blood as memory lymphocytes ready to respond immediately if the same antigen ever turns up again
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46
Q

What can be some side effects of a vaccine?

A

A mild fever or rash

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47
Q

What may prevent parents from getting their children immunised?

A

Media scares about the risks of immunisation

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48
Q

What are three risks of immunisation?

A
  • it’s common for a person to get redness or swelling around the site of the vaccination
  • some children may get a mild form of the disease they are being vaccinated against
  • very rarely a child suffers an allergic reaction
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49
Q

What are three advantages of immunisation?

A
  • a child can become immune to a disease without having to suffer it
  • the chances of any long-lasting harm is smaller than if a person actually got measles, mumps, rubella or diphtheria
  • if enough children get vaccinated, then it becomes so rare that even unvaccinated children are unlikely to get it
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50
Q

What is a primary response?

A

The response when a person is infected for the first time

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51
Q

What is the secondary response?

A

The response after a person is infected a second time when memory lymphocytes are used

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52
Q

What are monoclonal antibodies?

A

Large quantities of identical antibodies

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53
Q

What is a B lymphocyte?

A

A lymphocyte that has started producing antibodies and can’t divide anymore

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54
Q

How are monoclonal antibodies produced?

A
  • an antigen is injected into a mouse so that it produces B lymphocytes against it
  • myeloma(cancer) cells are grown in a culture medium
  • the B lymphocyte cells and the myeloma cells are fused, forming monoclonal antibodies
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55
Q

Why are monoclonal antibodies used?

A

To make large amounts of divisible B lymphocytes

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56
Q

What is a hybridoma?

A

A cell produced from the fusion of two other cells (a hybrid of both)

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57
Q

How are monoclonal antibodies used in pregnancy tests?

A

A dipstick covered in monoclonal antibodies is dipped in urine to see if any HGH, a hormone produced in the urine of pregnant women, is there. If it is, the HGH binds to the monoclonal antibodies on the stick and causes a colour change

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58
Q

Why do radiologists use monoclonal antibodies to tell where any blood clots or cancer cells are?

A

Monoclonal antibodies can be made slightly radioactive and can bind to the membranes of platelets or cancer cells. This allows radiologists to detect where the platelets or cancer cells are, as the radioactive monoclonal antibodies show up on X-rays

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59
Q

What damage can platelets cause when in the wrong place?

A

They can cause blood clots in the heart or the brain which can kill a person

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60
Q

What do platelets do?

A

Cause blood clots

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61
Q

What two things are given to patients to treat cancer?

A
  • ionising radiation (radiotherapy)

- drugs (chemotherapy)

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62
Q

What are the drawbacks of chemotherapy and radiotherapy?

A

It’s difficult to make sure that only cancer cells are targeted

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63
Q

What are three reasons drugs attached to monoclonal antibodies are useful for treating cancer?

A
  • the drug is only delivered to cells that need to be destroyed
  • less of the drug is needed and it isn’t wasted in parts of the body that are healthy
  • there is much less risk of harming healthy cells
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64
Q

What are metabolic reactions?

A

Chemical reactions happening within respiring cells

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65
Q

What waste products do metabolic reactions happening in respiring cells produce?

A

Carbon dioxide

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66
Q

What waste products do liver cells produce?

A

Urea

67
Q

What is urea produced from?

A

Excess amino acids

68
Q

How are the waste products of carbon dioxide and urea removed?

A

Carbon dioxide is removed from the blood by the lungs while urea is filtered out by the kidneys

69
Q

What does the renal artery do?

A

Bring blood to the kidneys

70
Q

What is produced from the substances filtered out by the kidneys?

A

Urine

71
Q

Where does the cleaned blood from the kidneys flow out of to get to the body?

A

The renal veins

72
Q

What happens to the urine produced in the kidneys?

A

It is excreted

73
Q

Why is a person’s life in danger when their kidneys stop working?

A

Because poisonous urea starts to build up in the blood

74
Q

What is the best treatment to use when a person’s kidneys can’t be repaired?

A

A kidney transplant

75
Q

What do the ureters do?

A

Carry urine from the kidneys to the bladder

76
Q

What does the bladder do?

A

Store urine

77
Q

What do the kidneys do?

A

Filter blood and make urine

78
Q

What four things are part of the urinary system?

A

The kidneys, ureters, bladder and urethra

79
Q

What does the urethra do?

A

Gets urine to flow through it and go outside the body

80
Q

Why can the kidney sometimes be rejected during a kidney transplant?

A

Kidney cells have antigens and this makes the immune system recognise that these are foreign cells. This means that the immune system can sometimes attack and kill these cells, and so reject the organ

81
Q

How can you lower the chances of a kidney being rejected?

A

You can make sure the antigens on the donated organ are similar to those on the patient’s cells

82
Q

Why does it take a long time to find a suitable kidney for a patient?

A

It is hard to find similar antigens to a patient’s cells

83
Q

Why do family members or close relatives commonly donate kidneys?

A

Because you can manage with one kidney and because they are more likely to have similar antigens than strangers

84
Q

Why are patients who get a kidney transplant more susceptible to diseases like colds?

A

They need life-long medication to prevent the kidney being rejected, which affects the body’s response to infection

85
Q

What treatment will a person waiting for a kidney transplant get?

A

Dialysis

86
Q

What are two drawbacks of dialysis?

A
  • they are expensive

- the patient will have to be connected to one for several hours, several times a week

87
Q

What are nephrons?

A

Tiny microscopic tubes found within the kidneys

88
Q

What four things does a nephron consist of?

A
  • Bowman’s capsule
  • convoluted tubules
  • loop of Henlé
  • collecting duct
89
Q

What does the Bowman’s capsule do?

A

Collect small molecules like water,urea and glucose from filtration of the blood brought from the glomerulus

90
Q

What is the glomerulus?

A

A network of capillaries which runs inside the Bowman’s capsule

91
Q

How does blood get to the glomerulus?

A

The renal artery

92
Q

How’s does the Bowman’s capsule carry out the process of filtration?

A

It has tiny holes which allow really small molecules like water, urea and glucose into the nephron from the glomerulus, and big molecules like proteins and red blood cells to stay within the blood

93
Q

What happens to the fluid running along inside the nephron after filtration in the Bowman’s capsule?

A

Selective reabsorption from the convoluted tubules

94
Q

What is selective reabsorption?

A

The reabsorption of useful substances the body needs to return to the blood such as glucose and water

95
Q

What is osmoregulation?

A

The regulation of the amount of water the body needs by selectively reabsorbing water

96
Q

What does the loop of Henlé do?

A

Help with osmoregulation

97
Q

Where does the selective reabsorption of glucose happen?

A

The convoluted tubules

98
Q

Where does the remaining fluid go when it reaches the end of the nephron?

A

Flows into the ureter

99
Q

What is the fluid left over at the end of the nephron called?

A

Urine

100
Q

What two things do the kidneys do?

A
  • filtration

- control the water content of the blood

101
Q

What are the kidneys controlled by?

A

The pituitary gland

102
Q

What hormone does the pituitary gland secrete to help control the water content of the blood?

A

ADH (antidiuretic hormone)

103
Q

What mechanism controls water content?

A

Negative feedback

104
Q

What is negative feedback?

A

A mechanism in which a change in a factor causes an action that reverses that change

105
Q

What is the effect of negative feedback?

A

It keeps things fairly constant even if their tendency is to keep changing

106
Q

What happens when the brain senses there isn’t enough water in the blood?

A
  • the pituitary gland secretes more ADH
  • the ADH causes the kidneys to reabsorb more water
  • a small volume of concentrated volume is produced
107
Q

What happens when the brain senses there is too much water in the blood?

A
  • the pituitary gland secretes less ADH
  • this makes the kidneys reabsorb less water
  • a large volume of dilute urine is produced
108
Q

What is the menstruation?

A

The breakdown and loss of the lining of the uterus along with the egg at the start of a woman’s menstrual cycle

109
Q

What is ovulation?

A

The release of an egg cell from an ovary

110
Q

What happens to the body in preparation for the egg cell?

A

The uterus lining thickens

111
Q

What two hormones are secreted by the ovaries to control the menstrual cycle?

A

Oestrogen and progesterone

112
Q

What happens to the uterus if an egg cell is fertilised?

A

The menstrual cycle stops and the thickened uterus lining stays in place so that the embryo can be embedded in it and start to develop

113
Q

On roughly what day of the menstrual cycle does ovulation begin?

A

Day 14

114
Q

On what days is fertilisation most likely to take place?

A

Days 14 to 16

115
Q

What two hormones secreted by the pituitary gland also control the menstrual cycle?

A
  • FSH (follicle-stimulating hormone)

- LH (luteinising hormone)

116
Q

What controls the release of FSH and LH?

A

The levels of oestrogen and progesterone

117
Q

What is the corpus luteum?

A

The follicle left over after an egg has been released

118
Q

What does the corpus luteum do?

A

Secrete progesterone

119
Q

What happens to levels of oestrogen as the egg follicle matures?

A

It increases

120
Q

What does the corpus luteum do once fertilisation occurs?

A

It continues to secrete progesterone

121
Q

Why are levels of progesterone kept high after fertilisation?

A

So that menstruation doesn’t occur so that the thick uterus lining is kept for the embryo

122
Q

What hormone must be in low levels in order for FSH to be released?

A

Progesterone

123
Q

What hormone must be in high levels for more LH to be released?

A

Oestrogen

124
Q

What are the effects of increasing progesterone levels on FSH and LH?

A

It inhibits its release

125
Q

What does FSH do?

A

Stimulate the growth and maturation of egg follicles within the ovaries

126
Q

What triggers ovulation?

A

A surge of LH

127
Q

Where are eggs created during the menstrual cycle?

A

Within follicles produced within the ovary after increasing levels of FSH

128
Q

What triggers menstruation?

A

The falling of oestrogen and progesterone

129
Q

What stimulates oestrogen production?

A

Maturing follicles

130
Q

What is the process of menstruation in terms of hormones?

A
  • it is the beginning of menstruation so there are low levels of oestrogen and progesterone
  • low levels of progesterone mean more FSH is released, stimulating the growth and maturation of follicles containing eggs
  • as the follicles mature, they release more oestrogen
  • this means a thickening of the uterine wall as well as an increase in the amount of LH released
  • an LH surge triggers ovulation, leaving behind a corpus luteum
  • the corpus luteum secretes progesterone
  • increasing progesterone inhibits FSH and LH release
  • if fertilisation doesn’t take place, oestrogen and progesterone levels fall, triggering menstruation
  • this means levels of FSH increase and the cycle starts again
131
Q

What are gametes (sex cells)?

A

Egg and sperm cells

132
Q

Is the nucleus of gametes haploid or diploid?

A

Haploid

133
Q

What is the structure of an egg cell?

A
  • nucleus
  • cytoplasm
  • cell membrane
134
Q

What is special about the cytoplasm of an egg cell?

A

There is a lot of it as it contains nutrients, including lipid droplets (shown as yellow spots)

135
Q

How does a sperm cell burrow into an egg cell?

A

It has an acrosome containing enzymes to digest its way into the egg

136
Q

Why does a sperm cell have a tail?

A

To swim

137
Q

What does the middle section of a sperm cell contain?

A

Mitochondria to release energy for respiration to get to the egg cell

138
Q

Why do egg and sperm cells have haploid nuclei?

A

So that when they fuse the embryo has a full set of genetic material and half the DNA from each parent

139
Q

What does the egg cell’s membrane do once a sperm cell’s nucleus enters?

A

It quickly changes so that no more sperm cell nuclei can enter

140
Q

What is a zygote?

A

The fusion of a sperm cell and an egg cell

141
Q

How does a zygote become an embryo?

A

It divides repeatedly to create a ball of cells

142
Q

What does an embryo do once it is formed?

A

It embeds into the uterus lining to grow and develop

143
Q

What does infertile mean?

A

Being unable to have children

144
Q

What are four possible solutions that could be used for an infertile couple to have children?

A
  • IVF
  • egg donation
  • surrogate mothers
  • hormones
145
Q

What does IVF stand for?

A

In vitro fertilisation

146
Q

What happens during IVF?

A
  • some of a woman’s egg cells are taken from her ovaries
  • these are fertilised in a dish with her partner’s sperm cells
  • one or two embryos are then put in her uterus to develop
147
Q

What is a problem of IVF?

A

Babies are born earlier more often than naturally conceived babies, which may cause problems at birth or in development later

148
Q

When is egg donation used?

A

When a woman isn’t producing eggs and another woman agrees to donate some

149
Q

What happens during egg donation?

A
  • a woman is given hormones to make her ovaries release eggs

- then IVF is carried out using sperm from the first woman’s partner

150
Q

What is a problem of egg donation?

A

A few women who donate eggs react badly to the high levels of hormones used to collect them

151
Q

When is a surrogate mother used?

A

When a woman isn’t able to grow a baby in her uterus

152
Q

What is a problem of using surrogate mothers?

A

The couple may have problems if the woman has developed a strong bond with the baby and doesn’t want to give it up

153
Q

Why are hormones used to help infertile couples?

A

Giving a woman extra hormones may help her ovaries to produce more eggs increasing the chances of fertilisation

154
Q

What are three of problems of giving women extra hormones for fertility problems?

A
  • increases the chances of her having more than one baby at a time
  • the babies tend to be born earlier than usual increasing the risk of problems at birth or later
  • some women react badly to the hormone treatment
155
Q

How many chromosomes do humans have in each of their body cells?

A

46

156
Q

How many sex chromosomes are there in humans?

A

2

157
Q

What do sex chromosomes do?

A

Determine gender

158
Q

What are women’s sex chromosomes?

A

XX

159
Q

What are men’s sex chromosomes?

A

XY

160
Q

What does the phenotype show?

A

What an individual looks like

161
Q

What does the genotype show?

A

The genetic material of the individual

162
Q

Why do flowers close during the night?

A

Being closed during the night means that they are protected from the wind,cold and damp

163
Q

What is a dialysis machine?

A

A machine that removes waste products from the blood

164
Q

Why are monoclonal antibodies used to make divisible B lymphocytes?

A

They can’t divide once they start producing antibodies however with the addition of the cancer cells they can

Biology extension edexcel (3 decks)

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