Multicellular organism Flashcards
What is the first step of mitosis
In the original parent cell, the chromosomes replicate and double Forming 2 identical chromatids joined in the centre by a centromere
What is the second step of mitosis
The nuclear membrane breaks down and the chromosomes shorten and thicken, becoming visible under a microscope
What is the third step of mitosis
The chromatids line up along the equator of the cell
What is the fourth step of mitosis
Spindle fibres attach to the chromatids
What is the fifth step of mitosis
Spindle fibres shorten pulling the chromatids apart to opposite poles of the cell
What is the sixth step of mitosis
The cytoplasm divides and a nuclear membrane forms
What is the last step of mitosis
2 diploid cells produced, containing the same genetic information as the original parent cell
What is a chromatid
An exact replica of a chromosome joined together with the chromosome it’s replicating
What is the equator of the cell
The region in the middle of the cell where the chromatid pairs line up before they are separated to the poles
What are spindle fibres
The spindle fibres are strand of protein that the cell uses to separate the chromatid pairs from the equator to the poles
What is a diploid cell
They have two matching sets of chromosomes high are replicated during mitosis
What does mitosis do
Provides new cells for growth and repair of damaged cells and maintains the diploid chromosome complement
What are stem cells
Unspecialised cells in animals that can divide in order to self-renew
What do stem cells have the potential to do
become different types of cells
how are stem cells obtained
from embryo at a very early stage
When can tissue stem cells be found in the body
Throughout life
What does the specialisation of cells lead to
The formation of a variety of cells, tissues and organs
What are multicellular organism made up of
Tissues and organs
Do organisms only perform on function
No
What are cells in organs specialised for
Their function
What are groups of organisms that work together called
Systems
What is the hierarchy
Cells-tissues-organs-systems
What can a response to a stimulus be
A rapid action or a slower response from a gland
What does the nervous system consist of
The central nervous system and other nerves
What does the central nervous system consist of
The brain and spinal chord
What is the cerebrum
The large folded area of the brain and is responsible for conscious thoughts, reasoning, memory and emotions
What is cerebellum
Found at the rear of the brain below the cerebrum an controls balance and coordination movement
What is the medulla
Found at the top of the spinal chord and contains groups of neurons that transit electrical impulses to the hearts and lungs to control the heart rate and breathing rate
What do electrical impulses do
Carry messages along neurons
What do chemicals Dow it’s these messages
Transfer the, between neurons at synapses
What are the three types of neurons
Sensory, inter and motor
What do receptors
Detect sensory input/stimuli
What do sensory neurons do
Pass the information to the CNS
What do inter neurons do
Operate within the CNS, which
processes information from the senses that require a response
What do motor neurons do
Enable a response to occur at an effector (muscle or gland)
What is the function of the reflex arc
To control reflex reactions in humans
What is the purpose of reflexes
To protect the body from harm
What can a response to a stimulus be
A rapid action from a muscle or as lower response from a gland
What can endocrine glands release
Hormones into the bloodstream
What are hormones
Chemical messengers
What does a target tissue have
Cells with complementary receptor proteins for specific hormones, so only that tissue will be affected by these hormones
What are the roles of insulin and glucagon in the blood glucose regulation
They are released by the pancreas in order to control blood glucose concentration
What is glycogen
A storage carbohydrate found in the liver and muscle of animals
What are the only cells that are haploid
Gametes
What are almost all cells in terms of amount of chromosomes
Diploid
What are the two types of gametes
Egg cells and sperm cells(pollen grains in plants
What organ produces the egg cell
Ovaries
What organ produces the sperm cell
Animals: testes
Plants: anthers
Where is the female gamete organ found
Ovule
What is fertilisation
The fusion of the nuclei of the two haploid gametes to produce a diploid zygote, which divides to form an embryo
What contributes to variation in a species
The combining of two parent genes
What is discrete variation
variation that tends to have phenotypes that do unto separate categories
What is continuous variation
variation that shows a wide range of values with each value falling anywhere within the range
What is a gene
A location on a chromosome where a section of DNA contains the codes for a particular protein
What is an allele
different forms of genes
What is a phenotype
the organisms physical appearance
What is a genotype
a statement of the alleles it has for a characteristic
What is a dominant allele
A dominant allele always shows in the phenotype, even if the individual only has one copy of the allele
What is a recessive allele
A recessive allele only shows if the individual has two copies of the recessive allele
What does homozygous mean
Individuals who are homozygous for a certain ry two copies of the same allele
What does heterozygous mean
Individuals who are heterozygous for a certain gene carry two different alleles
What is the letter P used to indicate
The original parents in the cross
What is F1 used to indicate
The first generation of offspring of the parental types
What is F2 used to indicate
The second filial generation which is comprised of offspring(s) resulting from a cross of the members of F1 generation
What is the recessive allele represented by in a monohybrid cross
A lowercase letter
What is the dominant allele represented by in a monohybrid cross
A uppercase letter
What are the reason why the predicted ratios of the offspring phenotypes are not always achieved
Fertilisation is a random process, the sample was not big enough
What are the plant organs
Roots stems and leaves
What is the upper epidermis
The top layer of the leaf which is thin and transparent to allow light to reach the palisade cells in the layer below
What is the palisade mesophyll
Main site of photosynthesis column shaped, tightly packed and have many chloroplasts
What is the spongy mesophyll
loosely arranged in an irregular shape with air spaces inbetween for gas exchange
What are veins
Composed of xylem vessels and phloem. The xylem brings water to the leaf cells and the phloem transports sugar from photosynthesis
What is the lower epidermis
A thin layer that aids the regulation of gas exchange containing stomata and guard cells
What is the stomata
Openings through which the exchange of ga stakes place which are surrounded by two guard cells
What parts of the plant are involved in water transport
Root hairs, xylem vessels, spongy mesophyll, guard cells and stomata
Where does water enter through
The plant root hairs
Where is the water transported through
Dead xylem vessels
What is the structure of a xylem vessel
Consisted of dead cells with a thick cell wall strengthened by ring of lignin
Why are xylem vessels lignified
To withstand pressure changes as water moves through the plants
What is the structure of a phloem tissue
Composed of two main cell types serve tube cells and companion cells
What is transportation
Teh process of water moving through a plant and its evaporation through teh stomata
How does water move from the soil to the air
Through osmosis to the root hairs, through osmosis from the root hairs to the xylem in the root, through osmosis from the xylem to the spongy mesophyll in the leaf, from the spongy mesophyll to the moist air space inside the leaf, water the moves through diffusion from the air space in the leaf through the stomata into the air
Describe the process of transpiration
Water on the surface of spongy and palisade cells evaporate into air space and diffuses out of the leaf. More water is drawn out of the xylem cells to replace the water that is lost.
What are the factors that can speed up the rate of transpiration
Light, temperature, wind speed, humidity, leaf surface area
How does light affect transpiration
In bright light transpiration increases
Explain why light affects transpiration in this way
The stomata open wider to let in more CO2 for photosynthesis
How does temperature affect transpiration
transpiration is faster in higher temperatures
Explain why temperature affects transpiration in this way
Evaporation and diffusion are faster at higher temperatures
How does wind speed affect transpiration
Faster in windy conditions
Explain why wind speed affects transpiration this way
Water vapour is quickly removed speeding up diffusion
How does humidity affect transpiration
Slower in his mid conditions
Explain why humdidity affects transpiration in this way
It slows down if the leaf is already mois
How does leaf surface area affect transpiration
More leaf Leads to faster transpiration
Explain why leaf surface area affects transpiration in this way
larger leaf has mores stomata So more water will be evaporating
What does blood contain in mammals
Plasma, red blood cells and white blood cells
What does blood transport
nutrients, oxygen and carbon dioxide
How are red blood cells specialised
By being biconcave in shape and having no nucleus and containing haemoglobin
How do red blood cells transport oxygen efficiently
In teh form of oxyhaemoglobin
How is oxyheamoglobin made
Oxygen + heamoglobin
What are white blood cells
Part of the immune system and are involved in destroying pathogens
what are pathogens
Disease-causing micro-organisms
What are the two main type of white blood cells involved
Phagocytes and lymphocytes
What do phagocytes do
Carry out phagocytosis by engulfing pathogens
What is the process of phagocytosis
A phagocyte detects a pathogen it captures it by flowing its cell membrane around the pathogen which is then trapped and digested by enzymes
What do lymphocytes do
Produce antibodies which destroy pathogens
Describe the pathway that oxygenated blood takes through the heart
The blood enters the heart through the vena cava and then enters the right atrium after it contracts the blood then flows to the right ventricle. When that contracts the blood leaves through the pulmonary artery and goes to the lungs. The now oxygenated blood returns to the heart through the pulmonary vein which then enters through the left atrium of the heart and then flows to the left ventricle. It then leaves the heart through the aorta to the rest of the body
What is the function of the right atria
Collects deoxygenated blood from the vena cava and passes it to the right ventricle
What is the function of the left atria
Collects oxygenated blood form the pulmonary vein and passes it to the left ventricle
Function of the right ventricle
Collects deoxygenated blood from the right atria and pumps it through the pulmonary artery
Function of the left ventricle
Collects oxygenated blood from the left atria and pumps it through the aorta
What is the functions of the heart halves
Between atria and ventricles-to prevent back flow from the ventricles to the atria
Exit of the ventricles- prevent back flow from the arteries to the ventricles
Function of the aorta
accepts oxygenated blood pumped at high pressure by the left ventricle and distributes it to the body
Function of the vena cava
Collects deoxygenated blood oozing at low pressure through the veins of the body and passes this blood to the right atria
Function of the pulmonary vein
Collects oxygenated blood oozing at low pressure from the lungs and passes this blood to the left atria
Function of the pulmonary artery
Accepts deoxygenated blood pumped at high pressure by the right ventricle and distributes it to the lungs
Function of the coronary artery
Accepts oxygenated blood pumped at high pressure by the left ventricle and distributes it to the heart muscles itself
What is the structure of an artery
They have thick muscular walls, a narrow central channel and carry blood under high pressure away from the heart
What is the structure of a vein
Have thinner walls, a wider channel and carry blood under low pressure back towards the heart
What do veins contain
Valves to stop the back flow of blood
What do capillaries form
Networks at organs and tissues
What features of capillaries allow efficient exchange of materials
One cell thick walls shortening the diffusion time, in very close contact with body tissue also decreasing diffusion distance
What are lungs
Gas exchange organs
What do lungs consist of
A large number of alveoli providing a large surface area
How are oxygen and carbondioxide absorbed to or from the many blood vessels
Through the thin alveolar walls
Where are nutrients from the food absorbed into
The villi in the small intestine
What do teh large number of thin-walled villi proved
A large surface area
