Biology paper 2 prep Flashcards
(145 cards)
1
Q
What is a cell?
A
A group of organelles working together to perform the same function
2
Q
What is tissue
A
A group of cells working together to perform the same function
3
Q
What is an organ
A
A group of tissues working together to perform the same function.
4
Q
What is an organ system
A
A group of organs working together to perform the same function
5
Q
What is an organism
A
A group of organ systems working together to perform the same function.
6
Q
What are the different organ systems
A
-The endocrine system
-The digestive system
-The reproductive system
-The nervous system
-The excretory system
-The circulatory system
-The respiratory system
7
Q
How does a 16 cell embryo form
A
The zygote splits by mitosis
-2 cells —> 4 cells –> 8 cells —-> 16 cells.
8
Q
What is differentiation
A
The process where cells become specialised
9
Q
What are the 2 types of stem cells
A
-Embryotic stem cell
-Adult stem cell
10
Q
What can embryotic stem cells do that adult stem cells can’t
A
They can differentiate into any cell type
11
Q
What are the benefits and disadvantages of using embryotic stem cells to treat diseases
A
-They can differentiate into any cell type so can treat many diseases
-It is seen as ethically wrong as the cells come from aborted fetuses which can be considered a human life.
12
Q
What are enzymes
A
Biological catalysts that increase the rate of reaction without being used up.
13
Q
What is the definition of digestion
A
The breakdown of large insoluble molecules into small soluble molecules.
14
Q
What is mechanical digestion
A
It breaks down food physically into smaller pieces, in the mouth (teeth) and the stomach lining.
15
Q
How does digestion occur in the mouth
A
The teeth physically breaks down food and chemical digestion occurs as amylase is secreted which digests starch into glucose.
16
Q
Where does food move to after it is ingested through the mouth
A
It passes down the pipe called the oesophagus.
17
Q
What is peristalsis
A
It is a process that moves food through the gut by muscular contractions that push the bolus down the oesophagus.
18
Q
How is food churned in the stomach
A
By lots of muscular contraction in the stomach lining.
19
Q
What is secreted into the stomach to kill pathogens and break down food
A
Hydrochloric acid
20
Q
What does protease do
A
Breaks down proteins into amino acids
21
Q
What happens once the stomach digests food
A
The stomach is emptied and food flows into the small intestine
22
Q
A
22
Q
What is bile
A
It is made in the liver, stored in the gall bladder and released into the small intestine
It emulsifies fats to increase the SA and neutralises stomach acid so enzymes in the small intestine don’t denature.
23
Q
How is villi benefitted for absorption
A
-Large SA
-Microvilli for larger SA
-Short diffusion distance
-Plentiful blood supply due to lots of capillaries.
24
Role of the Large intestine
Here water is reabsorbed back into thee blood
25
Where is faeces stored and egested
The rectum and the anus
26
What is excretion
the removal of waste products of metabolism
27
What is ingestion
Taking in of food into the body
28
What is metabolism
The rate at which chemical reactions take place
29
What is transpiration
The loss of water from the surface of a plant
30
Composition of blood
RBC
WBC
Platelets
Plasma
31
Role of the platelets
They clot the blood at the site of a wound
-Soluble fibrogens convert into insoluble fibrin.
32
How are pathogens prevented from entering the body
Skin acts as a barrier
HCL in the stomach destroy pathogens
Tears, nose hairs and eye lashes trap pathogens.
33
What is the role of phagocytes
They ingest pathogens and secrete digestive enzymes
34
What is the role of lymphocytes
-Recognises the antigens on the pathogens and secretes antibodies to destroy them
-They label pathogens so pathogens can be easily recognised by phagocytes
-They neutralise toxins produced by the pathogen
-Causes pathogens to stick together
35
How do vaccines work
Vaccinations contain a dead/weakened form of the pathogen
-Contains the pathogens antigens
-Lymphocytes recognise the antigens and produce antibodies
-Memory cells are created
36
Purpose of memory cells
They produce antibodies much faster and in larger volume to prevent pathogens affecting the body again.
37
Why are ventricle walls thicker than atria walls
Because they have to pump blood further and at a higher pressure
38
Why is the left ventricle wall thicker than the right ventricle
Because it has to pump oxygenated blood all over the body and at a higher pressure.
39
Why is the CS a double circulatory system
Because blood pumps into the heart twice for every one it passes around the rest of the body.
40
Where does the hepatic portal vein take blood from and to
The stomach and the small intestine ---> Liver
41
Renal =
Hepatic =
Pulmonary =
Coronary =
Kidney
Liver
Lungs
Heart
42
Role of coronary arteries
They provide the heart with it's own oxygen supply so it can contract and pump blood
43
Cause of coronary heart disease
Fatty deposits build up in the walls of the coronary artery preventing oxygen flow to the heart, also causing anaerobic respiration and the build up of lactic acid.
44
What are the ways excretion occurs in humans
Carbon dioxide from the lungs
Sweat from skin
Urea from kidneys
45
Feces are _____ not ______
egested not excreted
46
What are the 3 main components of the kidney
Bowman's capsule
Proximal Convoluted Tubule
Collecting Duct
47
What happens at Bowman's capsule
-Ultrafiltration occurs
48
What is ultrafiltration
Small molecules (glucose, ions, water, urea)
are forced out of the blood into bowman's capsule under pressure
49
Why don't proteins go through bowman's capsule
Because protein molecules are too large and don't fit - they stay in the blood.
50
What happens at the Proximal Convoluted Tubule
-Selective Reabsorption occurs, Glucose and some ions move back into the blood
-Energy is required for this, this is provided by active transport as they are moving across the concentration gradient.
51
What process occurs at the Collecting Duct
Osmoregulation
52
What is Osmoregulation
The controlling of water content in the blood
53
What happens when you have little to drink
-The hypothalamus detects low water content
-Sends a signal to the pituitary gland to release more ADH
-This makes the walls in the collecting duct more permeable to water meaning more water moves back into the blood by osmosis
-This means urine is highly concentrated and has a low volume
54
What happens when you have a lot to drink
-The hypothalamus detects high water content
-Sends a signal to the Pituitary gland to release less ADH
-Walls in the collecting duct become less permeable to water
-Less water is reabsorbed back into the blood
-Urine is a pale colour, low concentration and High in volume
55
What is the ureter
The vessel linking the collecting duct to the bladder.
56
What is the urethra
-The vessel taking urine out of the bladder
57
What is transported in the urethra
Sperm and urine
58
What is a stimulus
A change in the environment
59
What are the sense organs in humans
-Ear
-Eyes
-Nose
-Tongue
-Muscle
-Skin
60
Nervous system vs Hormonal system
-Nervous system involves electrical impulses whereas Hormonal system uses chemical messengers in the blood
-Hormonal system responses are longer-lasting
-Electrical impulses target a specific effector muscle, hormone releases are more wide-spread
-The release of hormones takes longer
61
CNS
Central nervous system, contains both the brain and the spinal cord.
62
What happens in a nervous response
The stimulus is received by a receptor
-The impulse then travels along the sensory neurone to the CNS
-Then the impulse travels to the motor neurone, as a neurotransmitter diffuses across a synapse and the impulse travels to the effector muscle/gland.
63
What happens in a reflex response
-The stimuli is received by the receptor
-The impulse travels across the sensory neurone to the relay neurone
-The impulse then is sent to the motor neurone where the effector muscle contracts to reduce harm.
64
Reflex responses are __________
Involuntary and don't involve the brain.
65
What is a synapse
The gap between two neurones where neurotransmitters are released that diffuse across the synapse.
66
What is homeostasis
Maintaining a constant internal environment
67
How does the skin aid heat loss?
-By sweating as it evaporates
-Hairs on the skin laying flat so less insulated air is trapped close to the body
68
Roles of the skin
-Sense organ for pain, touch and pressure
-Tough outer
-Prevents pathogens from entering
-Controls heat loss
-Prevents water loss
69
What happens when you are too hot (homeostasis)
-You sweat meaning evaporation occurs aiding heat loss
-Vasodilation occurs, Arterioles become wider meaning more blood can flow closer to the surface of the skin meaning more heat is lost by radiation.
-Hairs lay flat so less insulated air is trapped closer to the body
70
What happens when you are too cold (homeostasis)
-Hair stand up to trap insulated air close to the body
-Shivering causes muscle contractions which releases heat internally
-Vasoconstriction occurs, arterioles become narrower meaning less blood flows closer to the surface of the skin meaning less heat is lost by radiation.
71
How is blood sugar levels decreased when we've eaten
-Insulin is released from the pancreas
-Insulin converts soluble glucose into insoluble glycogen so it can be stored in the liver.
72
Process of sexual reproduction in humans
-2 parents required
-Gametes (egg and sperm) fuse together and fertilisation occurs
-Zygote is formed and mitosis occurs forming an embryo.
---> Sexual reproduction produces genetic variation
73
Characteristics of Asexual Reproduction
Only requires 1 parent
Much faster than sexual reproduction
Offspring are identical --> cloning
74
How is a 32 cell Embryo formed
-The gametes the egg and sperm fuse together and fertilisation occurs
-The first cell formed is a zygote
-Mitotic cell division occurs 5 times forming a 32 cell embryo.
75
Example of Asexual reproduction in plants
-Strawberry runners
-potato tubers.
76
Components of the female reproductive system?
-Ovaries
-Fallopian tubes
-Uterus
-Vagina
-Cervix
77
Role of the ovaries
Makes eggs and the hormones oestrogen and progesterone.
78
Role of the cervix
It is the entrance to the uterus
79
Role of the fallopian tubes
Eggs are transported here to the uterus and it is the site of fertilisation
80
Role of the uterus
-Where the zygote forms and where the embryo develops.
81
Role of the vagina
Penis delivers semen here during intercourse (cringe)
82
Role of the testes
Makes sperm and testosterone
83
Role of the sperm duct
Tube that transports semen from the testes to the urethra
84
urethra
Transports semen and urine out of the body
85
Role of the prostate gland
Contribute seminal fluid
86
Journey of a sperm cell to the egg
Enters the vagina and moves up the cervix into the uterus, then the sperm swims up the fallopian tubes where it fertilises the egg.
87
Role of the Placenta
Provides the fetus with amino acids, glucose and oxygen
Removes urea, carbon dioxide and waste minerals
88
Hormones in the female reproductive system
FSH
LH
Oestrogen
Progesterone
89
Role of FSH
Follicle stimulation hormone which means it causes the egg to mature
Secreted from the pituitary gland
90
Role of LH
Causes ovulation (the release of an egg from the ovary) secreted from the pituitary gland
91
Role of oestrogen
released from the ovaries and it inhibits the release of FSH and repairs the uterus lining
It also promotes female secondary sexual characteristics
92
Role of progesterone
It is released from the ovaries and it maintains the uterus lining
93
Role of testosterone
Produced in the testes and promotes male secondary sexual characteristics
94
Why is transpiration important for plants
It helps transport water and minerals from the roots to the leaves and regulates the plant's temperature
It also maintains turgor pressure in the cells
95
What is a genome
The entire DNA of an organism
96
What is the role of the nucleus
It controls the activites of the cell and stores genetic information.
97
How many chromosomes are in the human body
46, 23 pairs
98
What is the male sex chromosomes
XY
99
Female sex chromosomes
XX
100
What is a gene
A length of DNA that codes for a specific protein
101
Structure of DNA
Double helix
-Made up of sugar phosphate backbone
-Linking the two backbones are bases
102
Bases in DNA
Adenine - Thymine
Cytosine - Guanine
103
Nucleotide
3 units made up of
-deoxyribose sugar
-Phosphate
-Base - C,T,A,G
104
Differences between RNA and DNA
DNA is double stranded, RNA is single stranded
DNA is made up of deoxyribose sugar whereas RNA is made up of ribose sugar.
RNA has no Thymine but instead has uracil
105
Codon
Three bases found in mRNA and corresponds to a single amino acid
106
Anti-codon
A sequence of 3 bases on tRNA that matches the complimentary codon on mRNA.
107
What are the 2 main stages of protein synthesis
Transcription
Translation
108
What occurs during Protein Synthesis
-DNA unwinds to expose a single strand, exposing bases
-Unpaired bases in the nucleus match up the exposed DNA bases.
mRNA leaves the nucleus and attaches to a ribosome within the cytoplasm
tRNA molecules in the cytoplasm have complimentary anticodons that pair up with exposed mRNA bases producing amino acids
Amino acids form using a peptide bond forming a protein chain
109
How do gene mutations occur
-Inversion
-Deletion
-Substitution
-Duplication
110
How can chances of mutation increase
Exposure to ionising radiation such as gamma rays and X-rays.
111
Definition of environment
The total non biological living components in an ecosystem
112
Definition of Habitat
Specific place where an organism lives
113
Definition of Population
All the organisms that belong to particular species found in an ecosystem
114
Definition of Community
The population of all species found in an ecosystem
115
Producer
A producer is a plant that photosynthesises to produce food.
116
Consumer
A consumer is an animal which eats other animals and plants
117
Decomposer
Organism that breaks down dead material
118
Parasite
An organism which lives in another organism causing harm
119
Predator
An animal which hunts and kill another animal and eats it.
120
Biodiversity
The variety of plants and animals found within an ecosystem
121
Ecosystem
The interaction between the abiotic and biotic living factors in an environment.
122
What is fish farming?
When lots of fish are kept in a tank, optimum conditions are maintained with good water quality
Waste products constantly removed
Diets of fish are kept healthy, lots of protein
Fish isolated from predators to protect them
Sorted by size to prevent larger fish eating smaller fish
Fish with desired characteristics are selectively bred
123
What occurs during selective breeding
Humans select animals with desired characteristics and they reproduce
Offspring are then born with desired characteristics as alleles are passed down
Repeat over several generations
124
Can selective breeding occur in plants
Yes as plants can cross pollinate and produce off-spring with desired characteristics.
125
What does insulin do after a meal
Reduces blood sugar levels
126
How can a high amount of insulin be produced artificially
-Cut open a plasmid in a bacterial cell using restriction enzymes
-Use restriction enzyme to cut insulin gene
Insert insulin gene into plasmid using ligase enzyme
Place bacterial cell into fermenter
127
When does a plasmid become recombinant
When it has a different gene inserted into it.
128
Why does the fermenter need to be in sterile conditions?
To make sure there are no unwanted organisms
129
What are vectors
Vectors transport biological material from one place to another.
130
Examples of vectors
Plasmids and mosquitos.
131
How can plasmids act as vectors
-Small circular pieces of DNA
-Isolated from bacteria
-Desired gene inserted into the plasmid to make recombinant plasmids
-Inserted back into bacteria
132
How can viruses act as Vectors
Bacteriophage is a type of virus
-Desired gene is inserted into bacteriophage
-Bacteriophage attaches to cell wall of bacteria
-It injects genetic material into bacterial cell
-Desired gene taken up by bacterial DNA
133
Why are plants genetically modified
To improve food production or to improve resistance to herbicides
134
What are herbicides
Weed killer
135
Examples of GM plants
Golden rice - contains Vitamin A to prevent night blindness
Plants become resistant to herbicides.
136
What is a transgenic organism?
An organism where it contains genes that were transferred from another species.
137
What is a clone
A clone is a genetically identical organism
an example of this is 'dolly the sheep'
138
How to make a clone (animals)
-Remove the body cell from the animal
-Remove the egg cell from animal of the same species
-enucleate both cells
-Insert nucleus from the body cell into the empty egg cell.
-Fuse by electric shock
-Insert egg cell into the uterus of surrogate mother.
-The cell then divides by mitosis to form an embryo
-Clone of the mother is formed
139
Advantages of cloning over selective breeding
-Cloning is genetically identical
-Cloning is quicker
-More offspring are produced with cloning
-No need for two parents in cloning
140
What are the 2 types of cloning in plants
-Taking a cutting
-Micropropagation (tissue culture)
141
Describe the process of taking a cutting
-Cut a shoot of a plant and dip in rooting powder and transfer to soil
-Then grows into a new genetically identical plant
142
Describe the process of micropropagation
-Obtain small parts of a plant (explants)
-Place in agar jelly containing nutrients and hormones
-Explants then develop roots
-Transfer into soil in sterile conditions to avoid any microorganisms
-Provide optimum conditions for optimum growth
143
Advantages of tissue culture vs taking cuttings
-Tissue culture produces more plants as cuttings only produce one at a time
-Tissue culture can occur any time of the year
144
How can cloned transgenic animals be used to make proteins
-Using cloned transgenic animals means you can make large numbers of genetically identical animals
-These animals can then be used to produce human proteins.
