bio

Question 1

explain the formation of hydrogen between water and other polar molecules

Answer 1

hydrogen bonds form between hydrogen and a strongly electronegative element such as oxygen. in water hydrogen bonding helps to hold the water molecules together making it a stable substance

Question 2

why does methane have a lower boiling point than water

Answer 2

because methane does not have any hydrogen bonds, weakly held together.

Question 3

use an example: how are hydrophobic/philic molecules transported in blood

Answer 3

Hydrophilic molecules, which are attracted to water, require transport proteins to help them cross the cell membrane. Hydrophobic molecules, which repel water, can directly diffuse through the membrane via passive transport. Both types of molecules rely on the membrane’s selective permeability.

Question 4

why is amylopectin, even though similar to glycogen, less soluble?

Answer 4

more 1-6 glycosidic bonds in glycogen, more branching, more surface area to interact between molecules of water and glycogen, more solubility

Question 5

what makes the amino acids in proteins unique

Answer 5

r group

Question 6

define primary secondary tertiary quaternary structure

Answer 6

primary - sequence of amino acids in polypeptide chain

secondary - formation of α-helices and β-pleated sheets stabilised by hydrogen bonding. The secondary structure is the way a polypeptide folds in a repeating arrangement to form α-helices and β-pleated sheets

tertiary - tertiary structure is the further folding of the polypeptide stabilised by interactions between R groups
The tertiary structure is the way the polypeptide chain coils and turns to form a complex molecular shape (i.e. the 3D shape)
It is caused by interactions between R groups; including H-bonds, disulfide bridges, ionic bonds and hydrophobic interactions

quaternery - the quaternary structure exists in proteins with more than one polypeptide chain

Question 7

Which layer of the veins and arteries contains the muscle and elastic fibres?

Answer 7

Tunica media

Question 8

Which type of cell secretes mucus into the lumen of the small intestine to facilitate the movement of the chyme?

Answer 8

Goblet cell

Question 9

State the name of the molecule that CDKs attach to proteins in order to activate them.

Answer 9

phosphate group

Question 10

define detritivore

Answer 10

Detritivores are a type of heterotroph, or organisms that consume dead and decaying organic matter known as detritus to obtain energy and nutrition.

Question 11

define saprotroph

Answer 11

Saprotrophs are heterotrophs that obtain their organic nutrients from dead organisms by external digestion.

Saprotrophs are heterotrophs that ingest the tissues of dead organisms and waste material by secreting enzymes onto their food and digesting it externally before absorbing the products of this digestion. .

Question 12

define autotroph

Answer 12

Autotrophs make use of abiotic factors to produce their own food.

Question 13

what is nutrient cycling

Answer 13

The nutrient cycle is a system where energy and matter are transferred between living organisms and non-living parts of the environment. This occurs as animals and plants consume nutrients found in the soil, and these nutrients are then released back into the environment via death and decomposition.

Question 14

whats reproductive isolation

Answer 14

Reproductive isolation of populations can be temporal, behavioural or geographic. Reproductive isolation occurs when barriers prevent two populations from interbreeding – keeping their gene pools separate.

Question 15

what are abiotic factors

Answer 15

An abiotic factor is a non-living part of an ecosystem that shapes its environment. In a terrestrial ecosystem, examples might include temperature, light, and water.

Question 16

what is speciation

Answer 16

formation of a new species from an original, ancestral lineage

Question 17

how can reproductive isolation lead to speciation

Answer 17

reproductive isolation is when two or more populations of the same species are prevented from interbreeding. if the populations never interbreed then gene mixing between the populations stops and evolutionary forces such as natural selection may act differently on the populations. over time the populations may change to the point of not being able to interbreed and produce viable fertile offspring in which the case they would now be considered seperate species

Question 18

how does the ocean become more acidic

Answer 18

Typically, when carbon dioxide is dissolved in the ocean, it combines with water molecules to form carbonic acid (H2CO3)
The carbonic acid then dissociates to form bicarbonate ions (HCO3–) and hydrogen ions (H+)
The ocean also contains carbonate ions (CO3–), which are absorbed by coral and molluscs to form calcium carbonate (CaCO3)
Calcium carbonate is used to form the hard exoskeletons of reef-building corals and is used by molluscs to develop shells
H+ ions can reduce the stock of carbonate ions in the ocean by combining with it to form bicarbonate
Hence, the levels of H+ ions must be kept low to ensure that their is sufficient stock of carbonate ions for aquatic organisms

As a result of deforestation and the increased burning of fossil fuels, atmospheric carbon dioxide concentrations have increased
With more CO2 being absorbed by the oceans, there is an associated increase in the production of H+ ions
These H+ ions lower the pH of the ocean, causing acidification (ocean pH has dropped ~0.2 since the industrial revolution)
The H+ ions will also combine with carbonate ions, reducing the amounts available to marine organisms
This will result in the formation of thinner, deformed shells and reduce the population numbers of reef-building corals
The reduction in pH will also dissolve calcium carbonate structures, enhancing the damage to shells and corals

Autotrophs absorb both dissolved carbon dioxide and hydrogen carbonate ions and use them to produce organic compounds

Question 19

how is calcium carbornate and limestone created

Answer 19

When the hydrogen carbonate ions come into contact with the rocks and sediments on the ocean floor, they acquire metal ions

This commonly results in the formation of calcium carbonate and the subsequent development of limestone

Living animals may also combine the hydrogen carbonate ions with calcium to form calcium carbonate

This calcium carbonate forms the hardened exoskeleton of coral, as well as forming the main component of mollusca shells
When the organism dies and settles to the sea floor, these hard components may become fossilised in the limestone

Question 20

how is methane produced

Answer 20

Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground

Question 21

what are methanogens

Answer 21

Methanogens are archaean microorganisms that produce methane (CH4) as a metabolic by-product in anaerobic conditions

Question 22

what are anaerobic conditions

Answer 22

Wetlands (e.g. swamps and marshes)
Marine sediments (e.g. in the mud of lake beds)
Digestive tract of ruminant animals (e.g. cows, sheep, goats

Question 23

why is the methane level in atmosphere not very large even though it has significant quantity

Answer 23

The lifetime of methane gas once it reaches the atmosphere is around 10-12 years · This is because methane is oxidised in the atmosphere.

Question 24

what determines the impact of a gas in the atmosphere

Answer 24

The impact of a gas depends on its ability to absorb long-wave radiation as well as its concentration within the atmosphere

1. Ability to absorb long-wave radiation

Gases that have a greater capacity to absorb long-wave radiation will have a greater warming impact (per molecule)

2. Concentration within the atmosphere

The greater the concentration of a gas, the greater its warming impact will be within the atmosphere
The concentration of a gas will be determined by both its rate of release and persistence within the atmosphere

The overall impact of a greenhouse gas will be determined by the combination of both these factors

Methane has a larger capacity to absorb long-wave radiation than carbon dioxide, but is significantly less abundant
Water vapour enters the atmosphere rapidly but only remains for short periods, while carbon dioxide persists for years
Human activity is increasing the amount of greenhouse gases (except water vapour) and hence increasing their impact

Question 25

what are the consequences of ocean acidification

Answer 25

An increase in ocean acidification as a result of elevated anthropomorphic CO2 emissions could have several consequences:

The disappearance of coral reefs could result in a loss of shoreline protection and habitat, altering coastal ecosystems
The loss in revenue from tourism and food industries is predicted to cost economies upwards of $1 trillion by 2100
Increasing the dissolved CO2 levels in oceans would cause invasive species of algae to flourish (more photosynthesis)

Question 26

define heterozygous

Answer 26

each of the homologous chromosomes contain a different allele for the gene

Question 27

whats a homologous chromosomes pair

Answer 27

each chromosome of a homologous pair comes from a different parent
they contain the same sequence of genes for the same trait, but the versions of the genes (alleles) on each chromosomes may differ

Question 28

whats the significance of genes existing as alleles

Answer 28

alleles are different forms of a gene coding for the same trait. different alleles provide phenotypic variation for the expression of a gene.

Question 29

define mutation

Answer 29

gene mutation is a change in the nucleotide sequence of a section of DNA coding for a specific trait. New alleles are formed by mutation.

Question 30

what chemicals can cause mutagens

Answer 30

benzene

Question 31

what is a mutagen

Answer 31

A mutagen is a chemical or physical agent capable of inducing changes in DNA called mutations.

Question 32

what type of mutation/disease is sickle cell anemia

Answer 32

sickle cell anemia is a autosomal recessive disease caused by a point mutatin

Question 33

why is sickle cell anemia more prevelent in places with high malaria

Answer 33

he malaria parasite, Plasmodium, struggles to survive in sickled red blood cells, which tend to sickle under low oxygen conditions, making them less hospitable for the parasite. Additionally, sickled cells are more likely to be removed by the spleen, reducing infection rates. This protective effect has contributed to the persistence of the sickle cell trait in malaria-endemic regions, demonstrating an example of natural selection.

Question 34

whats ice age

Answer 34

Inherited variation exists within the population
Competition results from an overproduction of offspring
Environmental pressures lead to differential reproduction
Adaptations which benefit survival are selected for
Genotype frequency changes across generations
Evolution occurs within the population

Question 35

what are 3 ways of genetic variation

Answer 35

Mutations – Changing the genetic composition of gametes (germline mutation) leads to changed characteristics in offspring
Meiosis – Via either crossing over (prophase I) or independent assortment (metaphase I)
Sexual reproduction – The combination of genetic material from two distinct sources creates new gene combinations in offspring

Question 36

the binomial name system what comes first

Answer 36

genus in caps then species

Question 37

name and identify the 3 domains of life

Answer 37

Eukarya – eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)
Archaea – prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)
Eubacteria – prokaryotic cells lacking a nucleus and consist of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)

Question 38

whats the pneumonic for taxonomy

Answer 38

katie perry comes over for grape soda

Question 39

wings in birds and bats. analogous or homologous

Answer 39

analogous

Question 40

explain the figwort situation, why was it reclassified

Answer 40

Until recently, figworts were the 8th largest family of flowering plants (angiosperms), containing 275 different genera

This was problematic as many of the figwort plants were too dissimilar in structure to function as a meaningful grouping

Taxonomists examined the chloroplast gene in figworts and decided to split the figwort species into five different clades

Now less than half of the species remain in the figwort family – which is now the 36th largest among angiosperms

Question 41

difference between introns and extrons

Answer 41

introns are non coding part /region of dna

extrons are protein coding regions of dna

Question 42

define chromatin, chromatid, chromosome

Answer 42

Chromosomes: Chromosomes are long, coiled structures made of DNA and proteins that carry genetic information and are found in the nucleus of cells.

Chromatin: Chromatin is the less condensed form of DNA and proteins found in non-dividing cells, which allows for gene expression and DNA replication.

Chromatids: Chromatids are the two identical halves of a duplicated chromosome that are joined together at the centromere and separated during cell division.

Question 43

whats the word starting with t that was observed through the davson danielli model

Answer 43

trilaminar

Question 44

where does the pancreas secrete enzymes into

Answer 44

lumen

Question 45

what is secreted by the pancreas

Answer 45

amylase, lipase, endopeptidase

Question 46

what remains undigested

Answer 46

cellulose

Question 47

food travels down oesophagus as a b__

Answer 47

bolus

Question 48

whats the movement of contraction for digestion

Answer 48

Continuous segments of longitudinal smooth muscle rhythmically contract and relax (perstalsis)

Question 49

what is segmentation

Answer 49

Segmentation involves the contraction and relaxation of non-adjacent segments of circular smooth muscle in the intestines
Segmentation contractions move chyme in both directions, allowing for a greater mixing of food with digestive juices
While segmentation helps to physically digest food particles, its bidirectional propulsion of chyme can slow overall movement

Question 50

features of villi

Answer 50

Microvilli – Ruffling of epithelial membrane further increases surface area
Rich blood supply – Dense capillary network rapidly transports absorbed products
Single layer epithelium – Minimises diffusion distance between lumen and blood
Lacteals – Absorbs lipids from the intestine into the lymphatic system
Intestinal glands – Exocrine pits (crypts of Lieberkuhn) release digestive juices
Membrane proteins – Facilitates transport of digested materials into epithelial cells

Question 51

whats something that dialysis tubing is not but membranes are

Answer 51

Unlike the membranes of living cells, dialysis tubing is not selectively permeable based on charge (ions can freely cross)

Question 52

what did william harvey deduce/propose

Answer 52

arteries and veins part of a singular network

heart acts like pump

two circulation loops

double circulation

Question 53

whats atherosclerosis

Answer 53

plaque buildup via fatty deposits

Question 54

define pathogen

Answer 54

disease causing agent

Question 55

structure of aveleous

Answer 55

They have a very thin epithelial layer (one cell thick) to minimise diffusion distances for respiratory gases
They are surrounded by a rich capillary network to increase the capacity for gas exchange with the blood
They are roughly spherical in shape, in order to maximise the available surface area for gas exchange
Their internal surface is covered with a layer of fluid, as dissolved gases are better able to diffuse into the bloodstream

Question 56

what does surfactant do

Answer 56

reduce surface tension

Question 57

causes and consequences of emphysema

Answer 57

Emphysema is a lung condition whereby the walls of the alveoli lose their elasticity due to damage to the alveolar walls

The loss of elasticity results in the abnormal enlargement of the alveoli, leading to a lower total surface area for gas exchange
The degradation of the alveolar walls can cause holes to develop and alveoli to merge into huge air spaces (pulmonary bullae)

The major cause of emphysema is smoking, as the chemical irritants in cigarette smoke damage the alveolar walls

The damage to lung tissue leads to the recruitment of phagocytes to the region, which produce an enzyme called elastase
This elastase, released as part of an inflammatory response, breaks down the elastic fibres in the alveolar wall
Elastase activity can be blocked by an enzyme inhibitor (α-1-antitrypsin), but not when elastase concentrations are increased
A small proportion of emphysema cases are due to a hereditary deficiency in this enzyme inhibitor due to a gene mutation

Common symptoms of emphysema include shortness of breath, phlegm production, expansion of the ribcage, cyanosis and an increased susceptibility to chest infections

Question 58

main purpose of myelin sheath

Answer 58

he main purpose of the myelin sheath is to increase the speed of electrical transmissions via saltatory conduction

In myelinated neurons, the action potentials ‘hop’ between the gaps in the myelin sheath called the nodes of Ranvier
This results in an increase in the speed of electrical conduction by a factor of up to 100-fold

Question 59

where is melatonin produced

Answer 59

pineal gland

Question 60

purpose of melatonin

Answer 60

control circadian rythyms

Question 61

what causes the y chromosome

Answer 61

The SRY gene codes for a testis-determining factor (TDF) that causes embryonic gonads to form into testes (male gonads)
In the absence of the TDF protein (i.e. no Y chromosome), the embryonic gonads will develop into ovaries (female gonads)

Question 61

where is fsh secreted from

Answer 61

anterior pituitary

Question 62

describe the menstrual cycle

Answer 62

1. Follicular Phase

Follicle stimulating hormone (FSH) is secreted from the anterior pituitary and stimulates growth of ovarian follicles
The dominant follicle produces estrogen, which inhibits FSH secretion (negative feedback) to prevent other follicles growing
Estrogen acts on the uterus to stimulate the thickening of the endometrial layer

2. Ovulation

Midway through the cycle (~ day 12), estrogen stimulates the anterior pituitary to secrete hormones (positive feedback)
This positive feedback results in a large surge of luteinizing hormone (LH) and a lesser surge of FSH
LH causes the dominant follicle to rupture and release an egg (secondary oocyte) – this is called ovulation

3. Luteal Phase

The ruptured follicle develops into a slowly degenerating corpus luteum
The corpus luteum secretes high levels of progesterone, as well as lower levels of oestrogen
Estrogen and progesterone act on the uterus to thicken the endometrial lining (in preparation for pregnancy)
Estrogen and progesterone also inhibit secretion of FSH and LH, preventing any follicles from developing

4. Menstruation

If fertilisation occurs, the developing embryo will implant in the endometrium and release hormones to sustain the corpus luteum
If fertilisation doesn’t occur, the corpus luteum eventually degenerates (forming a corpus albicans after ~ 2 weeks)
When the corpus luteum degenerates, estrogen and progesteron levels drop and the endometrium can no longer be maintained
The endometrial layer is sloughed away and eliminated from the body as menstrual blood (i.e. a woman’s period)
As estrogen and progesterone levels are too now low to inhibit the anterior pituitary, the cycle can now begin again

Question 63

explain ivf

Answer 63

In the IVF process, down regulation involves using drugs to halt the secretion of FSH and LH, which subsequently stops the release of estrogen and progesterone, allowing doctors to control the timing and quantity of egg production in the ovaries; this treatment typically lasts about two weeks and is administered as a nasal spray. Following this, superovulation is induced by injecting large doses of FSH to stimulate the development of multiple follicles, which are then treated with human chorionic gonadotrophin (hCG) to mature the eggs before they are collected through aspiration. The extracted eggs are incubated with sperm to facilitate fertilization, and success is confirmed by microscopic analysis. About two weeks before implantation, progesterone treatments are started to prepare the endometrium. Healthy embryos are then selected and transferred into the uterus (or that of a surrogate), with multiple embryos often transferred to increase the chances of successful implantation, leading to pregnancy testing two weeks later to check for success.

Question 64

what is a stroke

Answer 64

sudden death of brain cells in a localised area due to inadequate blood flow

Question 65

what part of neural tube expands to form brain

Answer 65

anterior

Question 66

whats neuralation

Answer 66

neurulation refers to the folding process in vertebrate embryos, which includes the transformation of the neural plate into the neural tube. The embryo at this stage is termed the neurula

Question 67

what is a synapse

Answer 67

a junction at which a neuron transmits a signal to another cell

Question 68

how come strokes can be temporary

Answer 68

Strokes symptoms may be temporary if the brain is able to reorganise its neural architecture to restore function

Following a stroke, healthy areas of the brain may adopt the functionality of damaged regions
This capacity for the restoration of normal function is made possible due to the neuroplasticity of the brain

Question 69

name 2 strokes and function

Answer 69

Ischemic strokes result from a clot within the blood restricting oxygenation to an associated region of the brain
Hemorrhagic strokes result from a ruptured blood vessel causing bleeding within a section of the brain

Question 70

what part of brain controls autonomic activities

Answer 70

medulla

Question 71

sympathetic vs parasympathetic response

Answer 71

Sympathetic nerves release noradrenaline (adrenergic) to mobilise body systems (‘fight or flight’ responses)
Parasympathetic nerves release acetylcholine (cholinergic) to relax body systems and conserve energy (‘rest and digest’)

Question 72

whats red green colour blindness

Answer 72

genetic disorder whereby an individual fails to discriminate between red and green hues

Question 73

whats the word that amount of brain mass relative to an animal’s body mass

Answer 73

encephaliazation

Question 74

how much of body energy does brain consume

Answer 74

20%

Question 75

whats vestibular system

Answer 75

sensory system in the inner ear that is involved in balance and spatial orientation (proprioception)

Question 76

describe olfaction

Answer 76

Olfaction is the ability to detect airborne chemicals (odorants) as scents or smells

At the back of the nasal cavity is a patch of tissue called the olfactory epithelium, which is embedded with chemoreceptors

The olfactory epithelium is lined with mucus, in which odorant molecules will dissolve before binding to the chemoreceptors
Binding of an odorant molecule will trigger a nerve impulse, which is transferred via the olfactory bulb to the brain
The combination of olfactory receptors activated determines the specific scent perceived by the brain

Question 77

why are standard hearing aids ineffective in deaf patients

Answer 77

they amplify sounds but do not bypass defective hearing structures

Question 78

cochear implants contain 2 parts. they are….

Answer 78

external part (microphone, trnansmitter)

internal part (reciever/stimulator)

Question 79

describe how cochlea implants work

Answer 79

The external components detect sounds, filter out extraneous frequencies and then transmit the signals to the internal parts
The internal components receive the transmissions and produce electrical signals via electrodes embedded in the cochlea
The electrical signals are then transferred via the auditory nerve to be processed by the brain

1. Basic Function
   Cochlear implants are medical devices that bypass damaged parts of the ear and directly stimulate the auditory nerve to provide a sense of sound to individuals with severe hearing loss. They are designed for people whose hearing loss is caused by damage to the hair cells in the cochlea, which normally detect sound vibrations and convert them into electrical signals sent to the brain.
2. Components of a Cochlear Implant
   A cochlear implant consists of two main parts:

External components:
Microphone: Captures sound from the environment.
Speech processor: Selects and arranges sounds captured by the microphone.
Transmitter: Sends the processed signals to the internal implant via radio waves.
Internal components:
Receiver: Implanted under the skin, it converts the radio signals into electrical impulses.
Electrode array: A series of electrodes surgically implanted into the cochlea. These electrodes directly stimulate the auditory nerve by sending electrical signals that represent sound.
3. Mechanism of Action
Sound Detection: The microphone in the external part picks up sounds from the environment.
Sound Processing: The sound processor converts these sounds into digital signals. These signals are processed to emphasize certain frequencies, particularly speech sounds.
Transmission: The transmitter sends these signals to the internal receiver through a magnetic connection across the skin.
Electrical Stimulation: The internal receiver converts the digital signals into electrical impulses, which are sent to the electrode array inside the cochlea.
Nerve Stimulation: The electrodes stimulate different parts of the auditory nerve depending on the frequency of the sound. Low-frequency sounds stimulate deeper areas of the cochlea, while high-frequency sounds stimulate regions closer to the entrance.
Perception of Sound: The auditory nerve sends these electrical impulses to the brain, where they are interpreted as sound.
4. Limitations
Cochlear implants do not restore normal hearing but provide a useful representation of sounds.
They are most effective for individuals who have lost hearing later in life or have a short duration of deafness, as the brain is better able to interpret the signals.

Question 80

how does coal and peat form

Answer 80

Saprotrophic bacteria and fungi will decompose dead organisms and return nutrients to the soil for cycling
This decomposition process requires oxygen (cell respiration is required to fuel digestive reactions)
Waterlogged regions may lack oxygenated air spaces within the soil and thus possess anaerobic conditions
Anaerobic respiration by organisms in these regions produces organic acids (e.g. acetate), resulting in acidic conditions
Saprotrophic bacteria and fungi cannot function effectively in anaerobic / acidic conditions, preventing decomposition
Since the organic matter is not fully decomposed in waterlogged soils, carbon-rich molecules remain in the soil and form peat
When deposits of peat are compressed under sediments, the heat and pressure force out impurities and remove moisture
The remaining material has a high carbon concentration and undergoes a chemical transformation to produce coal

Question 81

how is oil and natural gas formed

Answer 81

Oil and natural gas form in anaerobic conditions at the bottom of seas and lakes when aquatic organisms die and are covered by layers of sediment, and are then compressed and heated.

Question 82

explain the process of lactose free milk

Answer 82

Lactose is the sugar found in milk. It can be broken down by the enzyme lactase into glucose and galactose. However some people lack this enzyme and so cannot break down lactose leading to lactose intolerance. Lactose intolerant people need to drink milk that has been lactose reduced. Lactose-free milk can be made in two ways. The first involves adding the enzyme lactase to the milk so that the milk contains the enzyme. The second way involves immobilizing the enzyme on a surface or in beads of a porous material. The milk is then allowed to flow past the beads or surface with the immobilized lactase. This method avoids having lactase in the milk.

Question 83

what are the advantages of lactose free milk

Answer 83

As a source of dairy for lactose-intolerant individuals
As a means of increasing sweetness in the absence of artificial sweeteners (monosaccharides are sweeter tasting)
As a way of reducing the crystallisation of ice-creams (monosaccharides are more soluble, less likely to crystalise)
As a means of reducing production time for cheeses and yogurts (bacteria ferment monosaccharides more readily)

Question 84

what did watson and crick find

Answer 84

DNA strands are antiparallel and form a double helix
DNA strands pair via complementary base pairing (A = T ; C Ξ G)
Outer edges of bases remain exposed (allows access to replicative and transcriptional proteins)

Question 85

what is a greenhouse gas

Answer 85

a gas in the atmosphere that causes the retention of heat in the atmosphere

Question 86

what is the greenhouse effect

Answer 86

retention of heat from sun by the earths atmosphere

Question 87

why is water vapor often left out on in greenhouse gases

Answer 87

amount of water vapor is related to temperature, dependent on other greenhouse gases

Question 88

whats the purpose of valves in the heart

Answer 88

prevent the backflow of blood into the atria and ensure the blood flows in the correct direction

Question 89

what organs digest lipids

Answer 89

pancreas and small intestine

Question 90

amalyase digests starch into…

Answer 90

maltose

Question 91

name the monosaccarides

Answer 91

glucose, fructose, galactose

Question 92

can amalyse break down 1-6 amylopectin bonds

Answer 92

no!

Question 93

what parts of digestive system secrete protein digesting enzymes into alimentrary canal

Answer 93

pancreas, stomach

Question 94

name a function of intestinal epithelium

Answer 94

permeable to nutrients

form a barrier against harmful substances

provide large SA for nutrients (microvillus)

Question 95

what type of bond does maltase break in maltose

Answer 95

glycosidic

Question 96

state 2 functions of persetalsis in small inestine

Answer 96

mixes food with enzymes to aid digestion

moves food along the intestine

Question 97

function of circular muscle

Answer 97

Contraction: When the circular muscles contract, they constrict the diameter of the lumen, effectively narrowing it.

Question 98

function of longitudinal muscle

Answer 98

moves food forwrd within gut

Question 99

define absorption

Answer 99

Digestion breaks down food into smaller, soluble molecules. These products of digestion then pass from the lumen of the intestine into the blood. They pass through the microvilli of the cell surface membrane and into the epithelium cells.

Question 100

what functions of submucosa help with transport of absorbed substacnes

Answer 100

blood vessels, lymph vessels

Question 101

draw the digestive system

Question 102

what tissue layer develops into brain and spinal cord

Answer 102

ecotderm

Question 103

what does notochord develop into

Answer 103

vertebrae

Question 104

how are neurons removed

Answer 104

apoptosis

Question 105

what does cerebellum do

Answer 105

unconscious functions such as balance and movement

Question 106

what does brocas area do

Answer 106

speech and writing

Question 107

purpose of enzymes in digestion

Answer 107

hydrolyses (breaks down) food

Question 108

what ph does the stomach have, and why?

Answer 108

around 2 ph.
this is because its lined by gastric pits that release digestive juices

Question 109

what cells in the stomach produce hcl

Answer 109

parietal cells

Question 110

what is the purpose of hcl in the stomach

Answer 110

hcl activates pepsinogen into its active form, pepsin. it also helps kill bactdria and denatures proteins

Question 111

name the 3 parts of the small inestine

Answer 111

duodenum, jejunum, ileum

Question 112

state the difference between the 3 parts of the small intestine

Answer 112

duodenum - chemical digestion

jejunum - absorption of carbs, proteins, nutrients

ileum - absorbs any remaining nutrients, eg vitb12, bile salts

Question 113

the main purpose of the large intestine is to absorb __ and __

Answer 113

water and electrolytes

Question 114

why is there two sites for amalyase secretion - one in the salivary glands, and one in the pancreas?

Answer 114

because salivary amylase is denatured in the stomach. more amalyse is secreted into the chyme from the pancreas once it has passed the stomach

Question 115

what does bile do

Answer 115

bile aids in the digestion of lipids, primarily triglycerides, through emulsification

Question 116

whats the purpose of capillaries

Answer 116

exchange oxygen and nutrients in the blood with co2 and waste products from the cell

Question 117

whats deamination

Answer 117

removal of amino acid groups from amino acids to create urea

Question 118

whats exergonic

Question 119

describe 4 processes needed for the spontaneous origin of life on earth

Answer 119

1. synthesis of simple organic molecules from inorganic compounds
2. assembly of these molecules into polymers
3. formation of a polymer that can replicate
4. packaging of these molecules into molecules into membranes with an internal chemistry different from surroundings

Question 120

Describe the characteristics of stem cells that make them potentially useful in medicine.

Answer 120

a. stem cells are undifferentiated cells;
b. embryo cells are stem cells;
c. stem cells have/retain the capacity to divide;
d. can be used to produce cell cultures/large number of identical cells;
e. can be used to repair/replace damaged/lost cells/tissue;
f. stem cells are undifferentiated / have not yet differentiated/specialized;
g. can differentiate/specialize in different ways / are pluripotent/totipotent;
h. can be used to form a variety of different tissues / form organs;
i. used in medical research;
j. used in treatment of named disease;
k. stem cells are pluripotent

Question 121

Discuss the advantages and disadvantages of the use of adult stem cells.

Answer 121

Advantages:
a. adult stem cells can divide endlessly / can differentiate
b. adult stem cells can be used to repair/regenerate tissues
c. fewer ethical objections than with embryonic stem cells
d. adults can give informed consent for use of their stem cells
e. adult source is not killed / source would not have grown into new human / no death of embryos used to provide stem cells
f. no rejection problems / patient’s own cells used
g. less chance of cancer/ malignant tumor development than from embryonic stem cells
h. most tissues in adults contain some stem cells

Disadvantages:
i. difficult to obtain/collect/find in adult body/very few available
j. some adult tissues contain few/no stem cells
k. adult stem cells differentiate into fewer cell types than embryonic cells /OWTTE

Question 122

Explain how multicellular organisms develop specialized tissues.

Answer 122

a. only some genes are expressed in each cell type/tissue;
b. tissues therefore develop differently/become differentiated;
c. example would be goblet cell

Question 123

Outline the functions of Rough Endoplasmic Reticulum and Golgi Apparatus:

Answer 123

Ribosomes on the Rough ER synthesize polypeptides for secretion and use outside of the cell. The golgi apparatus performs the function of modifying or altering the proteins. These proteins are secreted out of the golgi in vesicles, which transport them to the protein membrane.

Question 124

Describe the process of endocytosis.

Answer 124

The membrane is principally held together by weak hydrophobic associations between the fatty acid tails of phospholipids

This weak association allows for membrane fluidity and flexibility, as the phospholipids can move around to some extent

This allows for the spontaneous breaking and reforming of the bilayer, allowing larger materials to enter or leave the cell without having to cross the membrane (this is an active process and requires ATP hydrolysis)

The process by which large substances (or bulk amounts of smaller substances) enter the cell without crossing the membrane

An invagination of the membrane forms a flask-like depression which envelopes the extracellular material
The invagination is then sealed off to form an intracellular vesicle containing the material

There are two main types of endocytosis:

Phagocytosis – The process by which solid substances are ingested (usually to be transported to the lysosome)
Pinocytosis – The process by which liquids / dissolved substances are ingested (allows faster entry than via protein channels)

Question 125

What is the difference between absorption spectrum and action spectrum for photosynthesis?

Answer 125

The action spectrum represents the rate of photosynthesis at each wavelength of light while the absorption spectrum shows the percentage of light absorbed at each wavelength.

Question 126

Name one type of fossil fuel that was formed from partial decomposition of organic matter at the bottom of lakes and oceans millions of years ago.

Answer 126

oil
crude oil
gas
natural gas
petroleum
coal
Coal
methane
Methan

Question 127

What name is given to the membrane potential that must be reached in order for an action potential to be triggered?

Answer 127

threshold potential
threshold
threshold of excitation

Question 128

Explain the reasons for the reclassification of Prokaryotes and Eukaryotes into Eubacteria, Archaea and Eukaryota.

Answer 128

studies of (base sequences of) rRNA provided evidence for three domain classification;
differences in cell walls / Archaea and Eukaryotes have no peptidoglycan in cell wall, Eubacteria do have peptidoglycan in cell wall;
differences in membrane bonding compared to Eubacteria and Eukaryotes / Archaea have ether bonds in lipid membranes whereas others do not;
presence or absence of histone proteins / histone proteins present in all Eukaryotes, present in some Archaea, none in Eubacteria;
large diversity of the group categorized as prokaryotes prompted division into two domains;
similarities between Archaea more similar to Eukaryota than to Eubacteria;
facilitates study of origin/evolution of eukaryotes;

Question 129

Distinguish between Archaea and Eukarya.

Answer 129

a. membrane-bound organelles present in Eukarya but absent in Archaea;
b. 70S ribosomes in Archaea whereas 80S ribosomes in (cytoplasm of) Eukarya;
c. nuclear envelope in Eukarya, not in Archaea;
d. introns are present in Eukarya but only in some genes of Archaea;
e. histone proteins present in all Eukarya but only in a few Archaea;
f. the membrane lipid structure is unbranched in Eukarya but branched in Archaea;
g. Archaea can inhabit extreme habitats while Eukarya cannot;

Question 130

Outline how leptin controls appetite.

Answer 130

a. leptin suppresses/inhibits appetite
b. is secreted by adipose tissue
c. level is controlled by amount of adipose tissue/ongoing food intake
d. leptin targets cells in hypothalamus which is the appetite control centre in brain
e. causes hypothalamus to inhibit appetite
f. if amount of adipose tissue increases, blood leptin concentration rises

Question 131

Outline the unconscious control of the heart rate.

Answer 131

heart can contract without nervous stimulation/myogenic contractions;
SA node is pacemaker/generates heart beat/initiates each cardiac cycle;
stimulates atria to contract;
leading to contraction of ventricles;
nerves carry impulses from the brain to speed up and slow down the heart;
medulla of the brain monitors blood pressure;
epinephrine/adrenalin produced by adrenal gland
carried by blood to the heart
speeds up the heart rate;
autonomic/sympathetic and parasympathetic nervous system control;
sympathetic speeds up heart rate;
parasympathetic/vagus nerve slows heart rate back to normal/resting rate ;

Question 132

Define tidal volume and ventilation rate.

Answer 132

a. tidal volume: volume of air taken in with each inhalation/out with each exhalation;
b. ventilation rate: number of inhalations/exhalations/breaths per minute;

Question 133

Explain how an impulse passes along the axon of a neuron.

Answer 133

a. resting potential is –70mV / relatively negative inside in comparison to the outside;
b. Na+/K+ pumps maintain/re-establish the resting potential ;
c. more sodium ions outside than inside when at the resting potential;
d. more potassium ions inside than outside;
e. nerve impulse is an action potential that stimulates a wave of depolarization along the membrane/axon;
f. if neuron is stimulated/threshold potential/–50mV is reached sodium ion channels open;
g. sodium ions diffuse/move in;
h. Na+ move in causing depolarization;
i. potassium ion channels open / potassium ions diffuse/move out;
j. inside becomes negative compared with outside / potential across membrane restored / repolarization;
k. active transport of K+ into neuron and Na+ out of neuron restores resting potential;
l. Na-K pumps restore Na/K balance/resting potential
m. Myelin around the neuron insulates the axon
n. speeds the transmission
o. Myelin permits saltatory conduction
p. permits jumping from node to node

Question 134

Membranes of pre-synaptic and post-synaptic neurons play an important role in transmission of nerve impulses. Explain the principles of synaptic transmission.

Answer 134

a. synapse is gap between adjacent neurons;
b. arriving action potential depolarizes pre-synaptic membrane;
c. opens voltage-gated calcium channels in membrane;
d. causes influx of calcium ions;
e. causes synaptic vesicles to fuse with pre-synaptic membrane;
f. vesicles release/exocytose neurotransmitter into the synaptic cleft;
g. neurotransmitter diffuses/moves across synaptic cleft;
h. neurotransmitter binds to receptors on post-synaptic membrane;
i. change in membrane permeability;
j. sodium ions flow into post-synaptic neuron;
k. opens channels allowing sodium ions/potassium ions to diffuse;
l. initiation of action potential/depolarization in post-synaptic membrane;
m. removal of the neurotransmitter; by enzyme / cholinesterase;
n. inactivated neurotransmitter returns to pre-synaptic neuron;
o. stops effect on post-synaptic membrane;

Question 135

compare contrast rod and cone cells

Answer 135

rod
dim light
absorb all visible wavelengths
spread out throughout retina
One neuron connects many rods.

cone
Three types of cone cell (red, green, blue) absorb different groups of wavelengths
bright light
Concentrated in the centre of the retina.
One neuron connects to one cone cell

Question 136

State the four main areas of the cerebral cortex, and outline their functions

Answer 136

Frontal lobe Regulates higher intellectual functions and controls social behaviours.
Occipital lobe Responsible for input from the eyes and judging distance and perspective.
Temporal lobe Involved in the regulation of speech, memory and hearing.
Parietal lobe Responsible for movement, spatial awareness and the sense of touch.

Question 137

Explain how a doctor is able to diagnose brain death.

Answer 137

brain death is the medical definition of death;

doctors determine whether it is possible to preserve the life of the patient;

doctors will carry out more than one test to determine if treatment is possible;

without brain stem function, it might not be possible for the patient to live;

doctor will test pupil reflex by shining light into the eye of the patient;

if pupils do not constrict then this is a sign that the medulla oblongata may be damaged;

doctor may also observe any of the following: blinking response, the gag reflex, eye movement when the head is moved.

Question 138

explain sypmpathetic/parasympathetic nerves for pupils in response to light

Answer 138

In bright light, parasympathetic nerves trigger circular muscles to contract and cause the pupils to constrict
In dim light, sympathetic nerves trigger radial muscles to contract and cause the pupils to dilate

Question 139

define brain death

Answer 139

Brain death is defined as the permanent absence of measurable activity in both the cerebrum and brainstem

Question 140

label and draw eye

Question 141

Discuss the relationship between one gene and one polypeptide.

Answer 141

DNA codes for a specific sequence of amino acids. The DNA code for one protein is a gene. DNA is transcribed into mRNA. mRNA moves to a ribosome where it is translated into a polypeptide. Originally it was thought that one gene always codes for a polypeptide. Some genes do not code for a polypeptide. Some genes code for a transfer RNA and some sections of DNA code for regulators that are not polypeptides. Change in the gene structure will affect the primary structure of the polypeptide.

Question 142

Describe the relationship between genes, polypeptides and enzymes.

Answer 142

gene is a sequence of DNA bases;
DNA/gene codes for a specific sequence of amino acids/polypeptide;
enzymes are proteins/composed of polypetides;
sequence of amino acids determines tertiary structure/folding/shape of active site;
change in the gene/mutation will affect the active site/function of an enzyme;
enzymes are involved in replication/transcription of genes;
enzymes are involved in synthesis of polypeptides;

Question 143

Explain why DNA must be replicated before mitosis and the role of helicase in DNA replication.

Answer 143

two genetically identical nuclei/daughter cells formed during mitosis so hereditary information in DNA can be passed on ;
two copies of each chromosome/DNA molecule/chromatid needed;
helicase unwinds the DNA/double helix;
to allow the strands to be separated;
helicase separates the two complementary strands of DNA;
by breaking hydrogen bonds between bases;

Question 144

state 3 exceptions of cell theory and why

Answer 144

Giant Algae: one multi-nucleated cell that grows to a large size without separate cells.
Striated Muscle Fibres: large multi-nucleated fibre formed from fusion of muscle stem cells
Fungal Hyphae: Aseptate hyphae that do not contain cross walls.

Question 145

Rubisco, insulin, immunoglobulins, rhodopsin, collagen and spider silk protein functions

Answer 145

Structure

Collagen: A component of the connective tissue of animals (most abundant protein in mammals)
Spider silk: A fiber spun by spiders and used to make webs (by weight, is stronger than kevlar and steel)

Hormones

Insulin: Protein produced by the pancreas and triggers a reduction in blood glucose levels
Glucagon: Protein produced by the pancreas that triggers an increase in blood glucose levels

Immunity

Immunoglobulins: Antibodies produced by plasma cells that are capable of targeting specific antigens

Transport

Haemoglobin: A protein found in red blood cells that is responsible for the transport of oxygen
Cytochrome: A group of proteins located in the mitochondria and involved in the electron transport chain

Sensation

Rhodopsin: A pigment in the photoreceptor cells of the retina that is responsible for the detection of light

Movement

Actin: Thin filaments involved in the contraction of muscle fibres
Myosin: Thick filaments involved in the contraction of muscle fibres

Enzymes

Rubisco: An enzyme involved in the light independent stage of photosynthesis

Question 146

outline the Changes to the Earth’s atmosphere, oceans and rock deposition due to photosynthesis

Answer 146

Oceans

Earth’s oceans initially had high levels of dissolved iron (released from the crust by underwater volcanic vents)
When iron reacts with oxygen gas it undergoes a chemical reaction to form an insoluble precipitate (iron oxide)
When the iron in the ocean was completely consumed, oxygen gas started accumulating in the atmosphere

Atmosphere

For the first 2 billion years after the Earth was formed, its atmosphere was anoxic (oxygen-free)
The current concentration of oxygen gas within the atmosphere is approximately 20%

Rock Deposition

The reaction between dissolved iron and oxygen gas created oceanic deposits called banded iron formations (BIFs)
These deposits are not commonly found in oceanic sedimentary rock younger than 1.8 billion years old
This likely reflects the time when oxygen levels caused the near complete consumption of dissolved iron levels
As BIF deposition slowed in oceans, iron rich layers started to form on land due to the rise in atmospheric O2 levels

Biological Life

Free oxygen is toxic to obligate anaerobes and an increase in O2 levels may have wiped out many of these species
Conversely, rising O2 levels was a critical determinant to the evolution of aerobically respiring organisms

Question 147

visible light has wavelengths between..

Answer 147

400-700 nanometers

Question 148

whats the role of bacteria in nutrient cycling

Answer 148

they act as decomposers and convert nutrients into accessible forms to humans and animals

Question 149

whats the role of fungi in nutrient cycling

Answer 149

fungi are saprophytes
decomposers
returning nutrients to soil, converting it accessible to animals/ppl

Question 150

whats the role of plants in nutrient cycling

Answer 150

add their own decaying matter to soils

absorb nutrients in soil and make avaliabel to browsing animals

Question 151

whats the role of animals in nutrient cycling

Answer 151

break down nutrients from bacteria, plants, fungi

return nutrients via waste