1
Q
What is homeostasis?
A
Body’s ability to regulate and maintain a stable condition inside your body, regardless of changes to the external environment.
2
Q
What does the endocrine system do? (3)
A
- growth and development
- how your body uses energy
- appetite
3
Q
What does the endocrine gland secrete?
A
- chemical messengers called hormones
4
Q
What is a hormone?
A
chemical messages that are secreted from glands into the blood and affect cells in another part of the body
5
Q
What controls the release of hormones? eg
A
external stimuli
- light
- sound
- temp
internal stimuli
- blood pressure
- body temp
6
Q
What is the role of the pituitary gland?
A
- receives signals from brain
- master gland that signals other glands
7
Q
What are the hormones of the pituitary gland?
A
- growth hormones
- ADH (water balance)
8
Q
What is the role of the thyroid gland?
A
- regulates metabolism and energy balance
9
Q
What are the hormones of the thyroid gland?
A
- thyroxine (regulates body energy usage)
- calcitonin (regulates calcium and phosphate in blood)
10
Q
What is the role of the adrenal gland?
A
- release hormones that help body deal with stress
- increase heart rate and blood pressue in times of fright
- increase amount of energy avaliable to muscles
11
Q
What are the hormones of the adrenal gland?
A
- cortisiol (increases mental stimulation, breaks down fat and protein to glucose)
- adrenaline (stimulates heart rate, increases blood pressure, dilates pupils)
12
Q
What are the hormones of the pancreas?
A
- insulin (causes cells to take up glucose from blood)
- glucagon (causes the release of glucose from muscles and liver when blood glucose levels drop)
13
Q
What is the role of the pancreas?
A
- regulates blood sugar levels in blood
- hormones act on liver and muscles cells
14
Q
What is the role of the ovary?
A
- normal reproductive development and fertility
- release hormones that control menstrual cycle
15
Q
What are the hormones of the ovary?
A
- oestrogen (acts of breast tissue, development of female sexual characteristics)
- progesterone (acts on ovary, control menstruation in women, plays a role in pregnancy)
16
Q
What is the role of the testes?
A
- making testosterone
- producing sperm
17
Q
What are the hormones of the testes?
A
- testosterone (development of male sexual characteristics)
18
Q
What is the role of the pineal gland?
A
- control sleeping and waking patterns
19
Q
What are the hormones of the pineal gland?
A
- melatonin (levels are controlled by our body clock, production is reduced by being in bright light)
20
Q
What are some conditions in the body that need to keep constant?
A
- body temp at 37˚C
- amount of water inside our body
- blood sugar levels
21
Q
What is the stimulus response model?
A
SRCERN
Stimulus
Receptor
Control centre
Effector
Response
Negative Feedback
22
Q
What is the stimulus? eg
A
body temp is too low
23
Q
What is the control centre? eg
A
hypothalamus sends message to muscles and blood vessels
24
Q
What is the effector? eg
A
muscles start to shiver and blood vessles constrict to reduce heat loss
25
What is the response? eg
Body temp returns to normal
26
What is the negative feedback? eg
Message sent to brain to get effectors to stop
27
What is negative feedback?
Negative feedback is a response triggered by changed conditions and serves to reverse the change
28
What are the steps for blood glucose regulation?
1. TOO low glucose in blood
2. pancreas produces glucagon entering blood
3. insulin doesn't allow glucose to be absorbed by body cells
4. blood glucose INCREASED
29
What is the problems in diabetes type 1?
- pancreas does not produce insulin
30
What is the problem in diabetes type 2?
- pancreas cells do not respond properly
31
What is a positive feedback loop? eg
aims to increase effects of a stimulus
eg
- childbirth
- blood clotting
32
How do hormones know which cells are their target cells?
This is because the target cells have a special corresponding receptor that recognise the hormones. (like a key and lock)
33
Why is the pituitary gland known as the master gland?
It controls the functions of many of the other endocrine glands.
34
What are chromosomes?
- a strand or molecule of DNA
35
What are genes?
- segment of DNA
36
What are genes made of?
genes are sequences of DNA
37
What do genes code for?
specific proteins which code for traits
38
What is the difference between a gene and a genome?
A gene is a segment of DNA, where as a genome is an organisms full set of DNA containing lots of genes
39
What is the function of DNA?
DNA contains the instructions for making proteins which code for specific traits
40
What holds the two strands of DNA together?
hydrogen bonds
41
What is a nucleotide?
the basic building block of nucleic acids containing 3 components
42
What are the 3 components of a nucleotide?
- phosphate
- nitrogenous base
- deoxyribose sugar
43
What are the rules for base pairing?
adenine & thymine
cytosine & guanine
44
What is the main function of RNA?
- single stranded molecule
- function to direct the production of proteins
45
What are some similarities between DNA and RNA?
- both code for traits
46
What are some differences between DNA and RNA?
- number of strands (DNA =2, RNA =1)
- sugar (DNA = deoxyribose, RNA = ribose)
- base paring (DNA =AT, CG, RNA = AU, CG)
47
What are proteins and what is their function ?
- code for traits for organisms
48
What are proteins?
A molecule made up of amino acids.
49
What are the steps required to produce a protein from DNA?
transcription
translation
50
What occurs in transcription?
DNA -> mRNA
51
What happens in translation?
mRNA -> RNA (protein)
52
What are the main phases of the cell cycle?
Interphase
Mitosis
Cytokinesis
53
What occurs in interphase?
growth, copies DNA and carries out normal functions
54
What occurs in mitosis?
division of nucleus
55
What occurs in cytokinesis?
division of 2 nucleui and cell contents (cytoplasm) into 2 daughter cells
56
What are the 3 phases in interphase?
G1
S
G2
57
What is G1 and what happens?
Growth 1
- growth of cell size
- makes proteins
58
What is S and what happens?
DNA synthesis
- chromosomes are doubled
- each stand doubled is identical called a sister chromatid
- held together of centromeres
59
What is G2 and what happens?
Growth 2
- growth in sizez
- makes organelles (ribosomes, and mitochondria)
60
What proportion of the cell cycle of mitosis?
10%
61
What are the differences between cytokinesis in animal and plant cells?
Cytokinesis in animal
- cleavage furrow pinches down the middle to split to 2 daughter cells
- flexible membrane allows this
Cytokinesis in plant
- cell plate growth and divides cell in 2
- cell plate thickens to a cell wall
62
How is the cell cycle regulated to deal with problems?
There are 3 checkpoints in the cycle which prevent the division if -
- there are not enough nutrients
- nucleus not been replicated
- cell is damaged
G1/S
G2/M
M (metaphase)
63
How do mutations result in a lack of control of the cell cycle?
The mutations result in an out-of-control cycle, resulting in uncontrolled cell division, or not enough cell division
64
When does DNA replication occur in cells?
DNA synthesis phase of interphase
65
Why does DNA replication occur in cells?
DNA has to be copied before a cell divides as new cells will need identical DNA to their parent cells
66
What are the 2 enzymes involved in DNA replication?
DNA helicase
DNA polymerase
67
What is the role of DNA helicase?
DNA unzips, hydrogen bonds are broken. In 2 single strands
68
What is the role of DNA polymerase?
Builds new DNA strands that match the parents strands using free nucleotides
69
What does semi-conservative mean?
each newly made DNA molecule has one original (conserving) and one new strand of DNA from its parent mole
70
What is the name of the original strands of DNA?
71
What is the name of the new strands?
72
What is produced at the end of the process of DNA replication?
proteins!
73
What happens if errors occur in the process?
74
What types of cells undergo mitosis?
somatic
75
What types of cells DON'T undergo mitosis?
sex cells
76
Why do cells need to divide/reproduce?
for growth and repair
77
What are the 4 phases of mitosis?
PMAT
prophase
metaphase
anaphase
telophase
78
What occurs in prophase?
- DNA coils and becomes visible
- nuclear membrane breaks down
- spindle forms
79
What occurs in metaphase?
- chromosomes line up along the cells equator (middle)
80
What occurs in anaphase?
- sister chromatids separate and are pulled toward opposite poles of the cell by spindle fibres
81
What occurs in telophase?
- chromosomes uncoil
- nuclear mebrane re-forms
- cell plate/clevage furrow forms
82
Describe the cells produced through mitosis.
2 identical daughter cells are produced during mitosis
83
What happens if cells undergo too much mitosis?
There will be rapid uncontrolled cell division which can often lead to cancer.
Dynamic Science
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