Multicellular Organisms Flashcards
where does fertilisation take place in mammals
the oviduct
where are gametes produced in mammals
ovaries and testis
what is fertilisation?
the fusion of nuclei of two HAPLOID gametes to produce a DIPLOID zygote, which divides to form an embryo. In mammals this occurs within the oviduct of the female
what is the male part of a flower and what are the two components
the Stamen is the male part of a flower
it is made up of an Anther which produces pollen, and a Filament
what is the female part of a flower and what are the 3 components
the Carpel is the female part of the flower
it is made up of s Stigma, Style and Ovary
where are gametes produced in flowers
the Anther (male) and Ovary (female)
what is pollination
Pollination is the transfer of pollen grains from an Anther to a Stigma. It must occur before fertilisation can take place
what must happen before fertilisation in flowers and how does this happen
before fertilisation, the pollen nucleus mist be able to reach the ovule nucleus.
to do this, the pollen grains grow a pollen tube down from the stigma to the ovary.
the haploid male gamete travels down the pollen tube and fuses with the haploid female gamete nucleus to produce a diploid zygote, which divides to form an embryo
what is an ovule
female gamete in plants
what is a haploid cell
cells with a single set of chromosomes
what is a diploid cell
cells with a double set of chromosomes
what is mitosis
provides new cells for growth, repair of damaged tissues and replacement of dead or damaged cells.
Mitosis maintains the diploid chromosome complement. This is important so that no genetic information is lost
what are the 6 stages of mitosis
- The chromosomes appear as fine thread like structures in the nucleus
- the chromosomes become more visible. chromosomes made up of 2 identical chromatids
- chromosomes line up at the equator of the cell, the nuclear membrane disappears. Spindle fibres attach to the centromeres (centre) of each chromatid pair
- spindle fibres contract, pulling the chromatids apart. Each is now called a chromosome and is pulled to the opposite poles of the cell
- chromosomes clump together at opposite ends of the cell and the nuclear membrane reforms round each group of chromosomes
- the chromosomes become less obvious and the cytoplasm divides into two. Before cell division occurs again the chromosomes in each cell must make copies of themselves
centromere
structure that temporarily holds two identical chromatids together
chromatid
one of two identical replicas of a chromosome
chromosome
threadlike structure carrying genetic code found inside nucleus of living cell
equator
central region of the cell
what is specialisation
this is when plant or animal cells have a specific shape or structure which permits them to carry out a certain function
what is the role of red blood cells
to carry oxygen around the body
what is the pigment in red blood cells called
haemoglobin
what does oxygen and haemoglobin produce
oxyhaemoglobin
what are the 4 specialisations of red blood cells
- nucleus is disintegrated to provide more space for the transport of oxygen
- haemoglobin produced to carry oxygen as oxyhaemoglobin
- biconcave shape to increase surface area to allow faster absorption of oxygen
- small and flexible so they can travel through capillaries
what is the specialisation of the nerve cells and what allows this to happen
specialised to send messages as electrical impulses
- main body cell elongated
-extensions/ projections at the end to connect to other cells
what is the specialisation of the sperm cells and what allows this to happen
specialised to carry half genetic code to make a zygote during fertilisation
- tail to swim towards egg
- many mitochondria to provide energy
what is the specialisation of ciliated epithelia and goblet cells
-goblet cells produce mucus to trap dust and bacteria
- cilia (small hairs) have developed to beat and move mucus up
what is the specialisation of root hair cells and what allows this to happen
specialised to absorb water from soil
- large extension/ projection to increase surface area for absorption
- vacuole passes into extension to maximise osmosis
- no chloroplasts
what is the specialisation of the xylem and what allows this to happen
specialised to transport water in plants
- cells form a hollow tube
- strengthened with lignin to withstand changes in water pressure
what is the specialisation of phloem cells and what allows this to happen
specialised to transport sugar in plants
- cell walls pierced to form sieve plates
- organelles not needed have disintegrated- joined with companion cell which controls cell
what is the specialisation of the palisade mesophyll and what allows this to happen
specialised to carry out photosynthesis
- lots of chloroplasts
what is a tissue
made from a group of specialised cells with a similar structure and function, which all work together to do a particular job
what is an organ
made from a group of different tissues, which all work together to do a particular job
what is a system
made from a group of different organs, which all work together to do a particular job
what is the order from smallest to largest of tissues, systems, cells, organs
cells, tissues, organs, system
what are stem cells
unspecialised animal cells which can divide in order to self renew, they have potential to become different types of cells
involved in growth and repair
what are embryonic stem cells
stem cells obtained from very early stage embryos, are capable of becoming any type of body cell
what are tissue stem cells
found in specific parts of the body throughout life, are slightly more specialised and so can only become a few types of cells
what are the 3 medical uses of stem cells
bone marrow transplant- donor bone marrow cells introduced into patients bone marrow to replace cancerous cells
skin graft- stem cells isolated by enzymes to be obtained from small sin samples. Stem cells then sprayed over damaged area
cornea repair- stem cells from the edge of the cornea can be used to treat corneal damage due to chemical burning. Because their own stem cells are used, there is no risk of rejection
4 future uses of stem cells
treatments for diabetes, Parkinsons disease, Alzheimers disease
treat disorders such as multiple sclerosis
why are stem cells controversial
embryonic stem cells are taken from human embryos, which means that the embryo must be deconstructed- some people view this as the equivalent to murder.
what is the central nervous system (CNS) made of
the brain and spinal cord
it is connected to all parts of the body by nerves, which lead to and from organs and systems
what is the role of the nervous system
the nervous system ensures that all the parts of the body work together as a coordinated whole.
what is the role of the cerebrum (describe place in the brain)
responsible for mental processes e.g memory, reasoning, imagination, conscious thought and intelligence- info from senses
large bit of brain at the top
what is the role of the medulla (describe place in brain)
controls breathing rate and heart rate and digestion- involuntary actions
lowest part- above spinal cord, below cerebellum
what is the role of the cerebellum ( describe place in brain)
coordinates muscles to control balance and posture
curved part below cerebrum
how are messages carried along neurons
electrical impulses
what is the gap between neurons called
Synapse
how is info transported across a synapse
chemically
7 steps in the flow of information
- stimulus e.g bell ringing
- detected by receptors in ears
- impulses travel along sensory neuron
- information is sorted in the CNS
- impulses travel along motor neuron
- effector is a muscle
- response is running for lunch
how do reflex actions work
a stimulus causes a receptor to send an electrical impulse along a sensory neuron to the inter neuron which is found in the spinal cord.
a chemical message sends the info across the synapse.
from the inter neuron the electrical impulse passes along a motor neuron to make a muscle contract, pulling the arm away from danger e.g a hot surface
what is the order of neurons that info is passed along
sensory
inter
motor
4 examples of reflex actions
blinking, swallowing,iris contraction, response to hot objects
5 features of hormones
made of protein
they are chemical messengers
produced/ released by endocrine glands
carried in the blood
have a long term effect
what allows a hormone to only work on one type cell
the cells in the target tissues of a hormone have specific complementary receptor proteins on their surface
the hormone and the target tissue cell receptor are a complementary shape
what happens when there is an increase in blood glucose concentration
increase is detected in receptor cells in the pancreas
pancreas produces more insulin (less glucagon)
hormone travels in blood to the liver
excess glucose stored as glycogen
what happens when there is a decrease in blood glucose concentration
detected by receptor cells n the pancreas
pancreas produces more glucagon (less insulin)
hormone travels in blood to liver
glycogen converted to glucose
what is glucagon produced
when the glucose is gone
what is variation
differences between individuals of the same species
how does sexual reproduction contribute to variation
it combines the genes of 2 parents, and will result in offspring that have a variety of both genes (genetic information)
what is discrete variation
when members of a species can be divided into distinct e.g eye colour or fingerprint type.
Discrete variation involves a single gene
how is discrete variation plotted
on a bar chart
what is continuous variation
a type of feature which varies over a continuous range of values such as height, weight or hand span, there are no distinct groups
This variation is due to many gene (polygenic) and the environment
how must continuous variation be presented
in a histogram or line graph
how many alleles does the body have for each characteristic
two
how many alleles do gametes contain
only one for each characteristic
what is a genotype
the genetic make up e.g Rr
what is a phenotype
the outward appearance e.g rough
how is the dominant allele shown
capital letter, R, M, B
how is the recessive allele shown
lowercase letter, r, m, b
what does homozygous dominant mean
both of the alleles are the same. They are both DOMINANT e.g RR
what does homozygous recessive mean
both alleles are the same, They are both recessive e.g rr
what does heterozygous mean
one dominant allele and one recessive allele e.g Rr
what is a gene
a part of a chromosome which codes for a protein
what is an allele
different forms of a gene
what does it mean when a gene is dominant
the allele is always expressed in the phenotype of the organism, even if there is just one copy
what is a monohybrid cross
the study of the inheritance of one characteristic
what does P stand for in a monohybrid cross
parental generation
what does F1 stand for in a monohybrid cross
the first generation produced- offspring of the parents
what does F2 stand for in a monohybrid cross
the second generation produced- offspring of two members of F1
what are the organs in plants
roots, stems and leaves
name the different structures in a leaf cell from top to bottom
-cuticle (waterproof upper layer)
-upper epidermis
-palisade mesophyll
-spongy mesophyll (containing leaf vein which contains Xylem and Phloem)
- stoma/ stomata
- guard cells (two per stoma)
what is the function of the upper epidermis
transparent layer which allows light to pass to the next layer
function of palisade mesophyll
main site of photosynthesis
function of spongy mesophyll
cells surrounded by air spaces to allow gas exchange
function of vein in leaf cells
contains xylem and phloem, which transports water and sugar
function of lower epidermis
contains guard cells which form pores
function of guard cells
control the opening and closing of stomata
function of stomata
pores which allow gases in and out of the leaf
3 components in phloem
sieve tube
companion cell
sieve plate
2 components in xylem
lignin to strengthen
cell wall between cells broken down
why does a plant need 2 transport systems
to supply raw materials for photosynthesis and distribute the products
what is transpiration
the process of water moving through a plant and its evaporation through stomata
what are the 5 steps in transpiration
- photosynthesis produces glucose in the leaves. Sugar is transported in the phloem
- mineral ions enter by active transport
- water with dissolved minerals enter roots (root hairs) by osmosis
- the movement of water through the plant is called the transpiration stream- water and ions pass up xylem
- transpiration- water evaporates from stomata in leaves
what can be used to measure rate of transpiration
potometer
how does a bubble potometer work
measures the rate of water absorption
the rate of water uptake can be measured by the rate of movement of the air bubble being pulled along the capillary tube
how does a weight potometer work
the rate at which water is lost from the plant is measured. since 1cm cubed of water= 1g of mass of water.
when setting up a potometer a layer of oil is used to cover water or a polythene bag is placed around the apparatus to ensure water only evaporates from the leaves
4 factors affecting the rate of transpiration
increasing temperature- increase transpiration
increasing wind speed- increase transpiration
increasing light intensity- increases transpiration
increasing humidity- decreases transpiration
function of platelets
helps to form clots when blood vessels are damaged
function of plasma
glucose, carbon dioxide and urea dissolve within it to be carried around the body
function of red blood cells
transport oxygen and some carbon dioxide
function of white blood cells
involved in the immune response (fighting infections)
what do white blood cells destroy
pathogens
what are pathogens
disease causing micro-organisms such as bacteria, fungi or viruses
what are phagocytes
white blood cells which carry out phagocytosis
what is phagocytosis
a process by which a pathogen is engulfed and digested by the white blood cell. Any pathogen entering the body receives the same response- it is not specific
what are lymphocytes
a type of white blood cell which can produce antibodies
what do antibodies do
destroy pathogens by preventing them from infecting cells and signalling phagocytes. Each antibody is specific to a particular pathogen, due to proteins called antigens on the pathogen surface
what are the 4 chambers of the heart called (from top left to top bottom right)
right atrium
right ventricle
left atrium
left ventricle
what does the right ventricle do
pumps blood to the lungs
what does the left ventricle do and what feature does it have to aid this
pumps blood around the body
it has a thicker ventricular wall
describe the direction of blood flow, from deoxygenated to oxygenated
deoxygenated blood enters the heart from the body through the vena cava
it flows from the right atrium into the right ventricle and then into the lungs through the pulmonary artery, where is picks up oxygen and gets rid of CO2
it then flows through the pulmonary vein into the left atrium, through the left ventricles and then out through the aorta to be pumped around the body
what is a coronary artery
they carry oxygen and nutrients to capillary networks in the heart.
they branch off the aorta
function of the vena cava
transports deoxygenated blood back from the rest of the body into the heart
function of the pulmonary artery
transports deoxygenated blood from the heart to the lungs where it gains oxygen
function of the pulmonary vein
transports oxygenated blood from the lungs to the heart
function of the aorta
transports oxygenated blood from the heart to the rest of the body
what is an artery
carries blood away from the heart
narrow central channel with thick muscular walls with helps to withstand high pressure
most arteries carry oxygenated blood apart from the pulmonary artery
what is a capillary
form networks at organs and tissues (join arteries and veins)
walls are 1 cell thick to allow exchange of materials between blood and cells
create a large surface area for the exchange of materials
what is a vein
carry deoxygenated blood from vital organs to the heart
veins have thin muscular walls but a wide wide central channel to allow blood to travel easily at a low pressure
Veins have VALVES to prevent the back flow of blood
why is the absorption of materials necessary
oxygen and nutrients from food must be absorbed into the blood stream to be delivered to cells for respiration
waste materials such as carbon dioxide must be removed from cells into the bloodstream
how are substances absorbed
tissues contain capillary networks to allow the exchange of materials at a cellular level
3 features of surfaces involved in absorption of materials
large surface area
thin walls
extensive blood supply
these increase the efficiency of absorption
where does absorption take place
the lungs are the gas exchange (oxygen and CO2 are exchanged)
nutrients from food are absorbed into the villi in the small intestine
6 parts of the respiratory system
trachea- ring of cartilage
intercostal muscles
bronchus
bronchiole
alveoli (single alveolus)
diaphragm
what is an alveoli
the site of gas exchange in the lungs
describe how gas exchange works in the alveolus
oxygen diffuses through the thin alveolar wall into the blood capillary.
carbon dioxide diffuses through the thin alveolar wall from the blood capillary into the air sac
5 reasons why alveolus is so efficient at gas exchange
large surface area
thin alveolar walls
good blood supply
moist
dense capillary network
what does the large surface of an alveolus allow
absorption of a large amount of oxygen
what does the inner alveolar surface being moist allow
allows oxygen to dissolve
what does a thin alveolar wall allow
allows oxygen to diffuse into blood easily
what does the network of tiny blood vessels surrounding the alveoli allow
the picking up and transport of oxygen
what is digestion
the breakdown of large insoluble food molecules into small soluble food molecules that can be absorbed through the lining of the gut
what are the finger-like projections in the small intestine called
villi (one villus)
what is the thin lining of a villus called
epithelium
what is the function of the lacteal
absorbs the products of fat digestion (fatty acids and glycerol)
what is the function of the blood capillaries in the villi
absorbs products of carbohydrate (glucose) and protein digestion (amino acids)
how is the small intestines large surface created
long
folded
thousands of finger-like projections called villi
