Unit 2 Multicellular organisms Flashcards
What are chromosomes made up of?
2 Chromatids and opposite ends of the X shape and a Centromere that meets in the middle
What is a chromosome complement?
Every species of living organism has a number of chromosomes called it’s chromosome complement eg humans have 46 chromosomes (23 pairs)
What is the difference between haploid and diploid?
a cell which has 2 sets of matching chromosomes is known as diploid
a cell which has one set of chromosomes is called haploid these are sex cells
What happens with haploid cells for fertilisation?
sex cells must be haploid as the nuclei of two haploid cells (haploid sperm and haploid egg) fuse together during fertilisation to produce a diploid zygote
what is mitosis in cells?
mitosis is the process of producing new cells and provides new cells for the growth and repair of damaged cells while keeping the diploid chromosome complement
why do we need new cells?
new cells always need to be produced to replace damaged cells and allow growth to happen eg a skin cells life span is 2 weeks
what is the stages of mitosis?
- DNA of cell is duplicated
- Chromosomes become more visible, they shorten and thicken and are seen as a pair of chromatids
- chromosomes line up along equator of cell and spindle fibres attach to the chromosomes
- chromosomes pulled apart and spilt into separate chromatids and are moved to opposite ends of the cells
- nuclear membranes form around each region of DNA, cytoplasm divides between the 2 cells, the cell pinches in the middle and divides into two genetically identical daughter cells
what are stem cells?
stem cells are unspecialised cells, this means they have the potential to become different types of cells
stem cells can divide in order to self renew and they are involved in growth and repair
what is the hierarchy of the specialisation of cells?
cells —> tissues —> organs —> systems
what are the 2 parts of the nervous system?
The central nervous system(CNS) = Brain + spinal cord
Peripheral nerves = connect the CNS to all parts of body
What is the medulla?
The medulla is found at the bottom of the spinal cord
The medulla controls heart rate and breathing
What is the Cerebrum?
The cerebrum is the large folded area of the brain
The cerebrum is responsible for conscious thoughts, memory and emotion
What is the Cerebellum?
The Cerebellum is found at the real of the brain
The cerebellum controls balance and coordination movement
What are sensory receptors?
Sensory receptors are found in all parts of the
body, these detect sensory stimuli and produce a electrical signal which is picked up by sensory neurons that are carried to the CNS
how does information pass along neurons?
through electrical impulses
what are the three forms of neurons?
SIM
Sensory neurons
Inter neurons
Motors neurons
What do sensory neurons do?
Carry info from sensory receptors to CNS
What do inter neurons do?
Carry info BETWEEN sensory neurons and motor neurons within the CNS
What do motor neurons do?
Carry info from the CNS to effectors (muscles or glands)
What response do reflex reactions have?
an involuntary response, they have to be extremely fast so they bypass the brain and only travel through the spinal cord eg your hand burning
what is a synapse?
a synapse is a gap between each neuron that the electrical impulse has to cross to pass on its message
what are the chemicals that carry information across the synapse called?
neurotransmitters
what are hormones?
hormones are chemical messengers found in the endocrine system
what is the difference between hormones and neurons?
hormones are chemical messengers
neurons are electrical messengers
what is the endocrine system?
the endocrine system is made up of endocrine glands that release hormones into the bloodstream, the hormones travel to their target organ
what are target organs?
target organs have cells with complementary receptor proteins for specific hormones
what is homeostasis?
the maintenance of constant internal environment eg keeping your blood glucose levels at certain levels
how is blood glucose regulation controlled?
blood glucose regulation is controlled by 2 hormones insulin and glucagon.
What happens when there is an increase in glucose concentration?
The pancreas releases insulin in response, glucose is taken into muscle and liver cells and stores as glycogen then there will be a decrease in glucose concentration
what happens when their is an decrease in glucose concentration?
pancreas releases glucagon in response, liver cells break down glycogen and release stored glucose, then glucose concentration increases
what are the male gametes in animals and plants?
animal - sperm
plant - pollen
what are the female gametes in plants and animals?
animal - egg
plant - ovule
what do gametes carry?
50% genetic information from mother
50% genetic information from father
how much chromosomes are in body cells, gamete cells and fertilised egg (zygote) cells?
body cells (diploid)- 46 chromosomes
gametes (haploid)- 23 chromosomes
fertilised egg (zygote) - 46 chromosomes
where are the gametes in plants produced for each parent?
males - pollen is produced in the anthers
females - ovules is produced in the ovaries
where are the gametes in animals produced for each parent?
males - sperm is produced in the testes
females - eggs are produced in the ovaries
what is the process of fertilisation?
fertilisation is when the nucleus of the haploid speed and the nucleus of the haploid egg fuse together to form a diploid zygote
what is variation?
variation is the differences that exist between members of the same species
what are the 2 forms of variation?
discrete variation - characteristics controlled by one single gene eg. eye colour
continuous variation - characteristics controlled by more than one gene eg. height, shoe size
what are genotypes and phenotypes?
genotype - an indiviauais alleles for a particular characteristic
phenotype - physical appearance
what is an allele?
an allele is the different form of a gene which produces phenotypes
genetic info is stored in genes, alleles determine which form of that gene you have (eg blue eye colour)
what are dominant alleles?
dominant alleles always produce a certain phenotype
they are represented by a capital letter e.g A
what are recessive alleles?
recessive alleles aren’t shown in the phenotype if a dominant allele is present
represented as a lower case letter e.g a
what does homozygous mean?
an individual who has inherited two of the same alleles for a gene
these are represented as either 2 capital letters or 2 lower case letters e.g AA or aa
what does heterozygous mean?
an individual who has inherited two different alleles of a gene
this is represented by a capital letter and a lower case letter e.g Aa
will offspring always follow the expected phenotype ratio?
no because fertilisation is random
what do plants need water for?
to maintain turgor
for photosynthesis
to keep cool
how does water enter a plant?
water enters the root hairs by osmosis
water molecules move from a area of high concentration to an area of low concentration inside the root hair cells
what is the function of root hairs on plants?
to increase the surface area so more water molecules and minerals can be taken up
what are xylem?
xylem are tubes that plants use to transport water up through the plant, they are hollow dead tubes supported with lignin rings
what are phloem cells?
phloem is used to transport sugar up and down the plant unlike xylem they are alive
they have cells called companion cells to provide energy
what are the three structures within the phloem?
Sieve plate
Sieve tube
Companion cell
what is the vein made up of in a plant?
The Xylem and the Phloem
what is the cuticle in a lead structure?
the cuticle is a waxy protective layer that cuts down water loss
what is the epidermis (upper and lower) in a leaf structure?
the epidermis is like a skin where the stomata and guard cells are found
what is the palisade layer in the leaf structure?
the palisade layer is made up of tall, cylinder shaped cells where most photosynthesis takes place
what is the spongy mesphyll layer in the leaf structure?
this consists of irregularly shaped cells which don’t fit together, this will create space between the, for gases to move around
what are stomata?
stomata are small pores found on the underside of the leaf
they let water vapour and gassed in and out of the leaf
what do guard cells do with the stomata? i
the stomata is surrounded by 2 guard cells which control, the opening and closing of the stomata
what happens when a plant has a higher level of water?
the guard cells will become turgid and circe out opening the stomata which allows CO2 in and O2 out
water also evaporates out the stomata
what happens when a plant has a low level of water?
the guard cells lose water and close
gas exchange can’t take place and water is not lost
what is the process of movement of water vapour out the stomata known as?
transpiration
what is the process of transpiration?
water is taken into the root hairs from the soil by osmosis
water goes up through the plant through the xylem tubes
water is lost to the atmosphere by evaporation through an open stomata
what can affect the rate of transpiration?
increases rate of transpiration - high light intensity, warm temperatures, wind
decreases rate of transpiration - low light intensity, cool temperatures, humidity
what are arteries?
think elasticated walls, that can withstand high pressure
Arteries carry blood Away from heart
what are veins (blood)?
contains valves to prevent back flow of blood
carry blood to heart
what are capillaries?
thin, one cell thick walls to allow gas exchange
very low blood pressure
what are the 4 types of blood cells?
red blood cells
white blood cells
platelets
plasma
what are red blood cells?
red blood cells are specialised to transport oxygen
contain lots of protein called haemoglobin, that bind to oxygen to produce oxyhaemoglobin
biconcave shape to maximise surface area
no nucleus
small and flexible to squeeze through capillaries
what are white blood cells?
Part of the immune system:
contains phagocytes that engulf and digest pathogens by phagocytosis
contains lymphocytes that produce antibodies that destroy pathogens
what are platelets?
they stop us bleeding
circulate around the blood and clump together when they find damaged blood cells
as the clot dries out a scab forms
what is plasma?
liquid component of blood
makes up over 50% of your blood
transports carbon dioxide, hormones and digested food
what is the heart?
the heart is responsible for pumping blood around the body
deoxygenated blood taken to lungs to pick up oxygen
oxygenates blood transported around the body
what are the 4 chambers of the heart?
right atrium
right ventricle
left atrium
left ventricle
what are the blood vessels of the heart?
Vena Cava
Pulmonary Artery
Pulmonary Vein
Aorta
Coronary artery
what is the function of the vena cava in the heart?
brings deoxygenated blood from body to heart
what is the function of the pulmonary artery in the heart?
takes blood to the lungs
what is the function of the pulmonary vein in the heart?
brings oxygenated blood from the lungs to the heart
what is the function of the aorta in the heart?
pumps oxygenated blood around the body
what is the function of the coronary artery in th heart?
provides the heart with its own blood supply
Why is the muscular wall of the left ventricle thicker than the right?
because the left ventricle has to pump blood all around the body rather than just around the lungs
what is the structure of the lungs?
trachea
bronchus
bronchiole
alveoli
what is the alveoli?
the alveoli is the site of gas exchange in the lungs
what makes the alveoli good at gas exchange in the lungs?
thin lining - it has thin lining so gas can quickly diffuse through it
large surface area - increases the area for gas to diffuse
good blood supply - dense capillary network so large volume of gas can be exchanged
what is the small intestine?
once food is digested it’s nutrients need to be absorbed, the small intestine has specialised structures called villi to help absorption
why are villi so good at absorbing food or nutrients?
thin walls - food absorbed quickly and easily
blood capillaries- absorbs amino acids and glucose
lacteal - absorbs fatty acids and glycerol
