Nat 5 - Multicellular Organisms Flashcards
Define the term multicellular organisms
Organisms that are made up of many cells
Describe the organisation of multicellular organisms
Multicellular organisms are organised into cells, tissues, organs and organ systems
Explain the significance of cell specialisation in multicellular organisms
It is very efficient as it ensures that cells do not have to carry out every function essential for the maintenance of life - they only carry out the function they’re specialised for, which saves energy.
Define the term stem cell
An unspecialised animal cell involved in growth and repair
State the type of organisms in which stem cells are found
Animals
Name two functions of stem cells in humans
Growth and repair
Define the term meristem
Site of production of non-specialised cells in plants and the only site of mitosis in the plant
State the type of organisms in which meristems are found
Plants
Name the process that occurs at a meristem
Cell division/mitosis
State the location of meristems
Shoot and root tips of plants
Describe the function of meristems
To carry out cell division to produce non-specialised cells
Name the components of the nervous system
Brain, spinal cord and nerves
Explain the function of the nervous system
To coordinate and control functions of the body
Name the components of the central nervous system
Brain and spinal cord
Name the three main parts of the brain
Cerebrum, cerebellum and medulla
Describe the function of each part of the brain
Cerebrum - memory and reasoning
Cerebellum - balance and muscle contraction
Medulla - breathing and heart rate
Name the three types of neurons
Sensory neuron, relay neuron and motor neuron
Describe the function of each type of neuron
Sensory - passes information to the CNS
Relay - passes information from sensory to motor
Motor - enables a response to occur by passing information to the effector
State the type of message that is passed through the nervous system
Electrical signal
State the speed of transmission of a nerve impulse
Very fast
Define the term receptor
A receptor detects changes in the environment called stimuli
Define the term effector and give two examples
An effector carries out the response to a stimulus. Examples of effectors are muscles and glands
Define the term synapse
The gap between two neurons
Describe how information is passed across a synapse
A chemical transmitter is released which diffuses across the gap
Describe how impulses are transferred in a reflex arc
Through neurons
Give two examples of reflex actions
Coughing
Pulling hand away from heat
Knee jerk reflex
Explain the importance of reflex actions
To protect the body from harm
Define the term hormone
A chemical messenger
Name the glands that release hormones
Endocrine glands
State how hormones travel around the body
In the bloodstream
Compare the speed of communication in hormone to the speed of nerve impulses
The speed of communication in hormones is much slower than the speed of nerve impulses
Explain why only target tissues/organs are affected by specific hormones
Target tissues/organs have protein receptors that pick up the signal from a hormone. Only certain tissues/organs are affected by each hormone because only certain tissues/organs have these receptors
State the function of insulin
It controls and regulates glucose levels in the blood
Describe the conditions necessary for insulin to be released
High blood glucose levels
State the name of the organ that releases insulin
Pancreas
Describe the effect that insulin has on blood glucose levels
It lowers blood glucose levels back down to normal
Name the storage carbohydrate in humans and state the location in which it can be stored
Glycogen - stored in the liver
State the function of glucagon
It controls and regulates glucose levels in the blood
Describe the conditions necessary for glucose to be released
Low blood glucose levels
State the name of the organ that releases glucagon
Pancreas
Describe the effect that glucagon has on blood glucose levels
It increases blood glucose levels back to normal
Define the term gamete
Sex cell
Name the female gamete in plants and animals
Animals - egg
Plants - ovule
Name the male gamete in plants and animals
Animals - sperm
Plants - pollen
Name the site of production of each type of gamete
Sperm - produced in testes
Egg - produced in ovary
Pollen - produced in anther
Ovule - produced in ovary
Define the term diploid
Containing two sets of chromosomes
Name four examples of diploid cells
Liver cell, kidney cell, skin cell and a zygote
Define the term haploid
Containing one set of chromosomes
Define the term fertilisation in animals
When the nucleus of the sperm fuses with the nucleus of the egg
Define the term zygote
The diploid cell formed as a result of fertilisation
Define the term chromosome complement
The whole set of chromosomes for a species e.g. The chromosome complement for humans is 46 (including sex cells)
Define the term variation
The differences that exist between species within a population
Describe how variation is increased in organisms
By combining genes from desperate parents
Define the term fertilisation in plants
When the nucleus of the pollen fuses with the nucleus of the ovule
Define the term discrete variation
Variation for characteristics that fall into distinct groups and are usually observed
Give three examples of discrete variation
Eye colour, blood type, ear lobe type
State the number of genes that give rise to discrete characteristics
One
Define the term continuous variation
Variation for characteristics that have a wide range of values and are usually measured
Give three examples of continuous variation
Height, weight and length of foot
Define the term polygenic
Controlled by lots of genes
State which type of variation is the most common in the phenotype of organisms
Continuous variation
Define the term allele
Different forms of a gene e.g. Blue and brown are different forms of the eye colour gene
Define the term genotype
The combination of genes an individual has
Define the term phenotype
The appearance of an individual based on its genes/visible characteristics
Define the term dominant
The allele that is seen in the phenotype
Define the term recessive
The allele that is masked by the dominant in the phenotype
Define the term homozygous
Two of the same alleles in a genotype
Define the term heterozygous
Two different alleles in a genotype
Define the terms P, F1 and F2 generations
P - parent generation
F1 - first generation of offspring after the parents
F2 - generation produced when the F1 is crossed
Explain why actual phenotype ratio differs from expected phenotype ratio
Fertilisation is a random process
Name the process by which water enters the plant
Osmosis
Name the cells that absorb water in the plant
Root hair cells
Name the vessel that transports water and minerals
Xylem vessels
Name the material that supports xylem vessels
Lignin
State if xylem vessels are living or non-living
Non-living
Explain why water needs to be transported by the plant
It is the raw material used for photosynthesis
Define the term transpiration
The loss of water through the leaves
Name the leaf structure that allows water loss from the plant and state its location
Stomata - located in small pores of the leaf in plants
Describe how the stomata is opened and closed
Guard cells
Name the process that allows water to escape from the plant
Evaporation
Name the vessels that transport sugar in the plant
Phloem vessels
State the direction of transport of sugar
Upwards and downwards (to supply all the cells with energy)
State if phloem vessels are living or non-living
Living
Name three substances that are transported in the blood in animals
Glucose, oxygen and carbon dioxide
State the function of the heart
The main function of the heart is to pump blood to the lungs to become oxygenated blood and to supply the rest of the body with oxygenated blood
Name the four chambers in the heart
Right atrium, right ventricles, left atrium and left ventricle
State the location of valves in the heart
Two valves are situated between the atria and the ventricles. The other two are situated between the ventricles and the two arteries that leave the heart
Explain the importance of valves in the heart
To prevent back flow of blood
Define the term oxygenated blood
Blood is is full of oxygen from the lungs
Define the term deoxygenated
Blood that has had most of its oxygen removed
Describe the function of the aorta
It carries blood oxygenated bloody from the left ventricle to the body
Describe the function of the vena cava
It carries deoxygenated blood from the body to the right atrium
Describe the function of the pulmonary artery
It carries deoxygenated blood from the right ventricle to the lungs
Describe the function of the pulmonary vein
It carries oxygenated blood from the lungs to the left atrium
Describe the pathway of blood as it travels through the heart and associated blood vessels
Blood flows from the right atrium to the right ventricle, up through the pulmonary artery to the lungs. Blood then travels through the pulmonary vein to the left atrium, then to the left ventricle and out the aorta to the body. Blood then travels through the vena cava back to the right atrium.
Name the blood vessels that supply the heart muscle with blood
Coronary arteries
Name the three types of blood vessels
Arteries, veins and capillaries
State the function of each of the three blood vessels
Artery - to carry blood at high pressure away from the heart
Vein - to carry blood under low pressure back into the heart
Capillary - to exchange materials
Compare the structure of each of the three blood vessels
Artery - thick walls, narrow central channel
Vein - thin walls, wide central channel, contains valves
Capillary - thin walls, large surface area, in close contact with living cells in tissues and organs
Describe two features of capillaries that make them efficient at their job
They have thin walls and a large surface area (they are also in close contact with living cells in tissues and organs) for exchange of materials
Describe the function of red blood cells
To carry oxygen around the body
Describe three ways in which the structure of red blood cells relates to their function
They contain haemoglobin which sticks to oxygen molecules. They have a biconcave which allows them to travel through small blood vessels to provide a large surface area for exchange of materials
State the function of cartilage in the respiratory system
To keep the airways open
Name the two gases that are exchanged in the alveoli
Oxygen and carbon dioxide
State three features of alveoli that make them efficient at gas exchange
Thin walls, large surface area and rich blood supply
Describe the function of mucus and cilia in the respiratory system
The mucus traps any dirt and bacteria in the trachea and the cilia sweeps mucus containing trapped dirt and bacteria up and away from the lungs
Describe the process of peristalsis
The movement of food through the digestive system. Muscles behind the food are contracted and muscles in front of the food are relaxed/expanded
Describe the process that occurs in the small intestine
Absorption of soluble products of digestion go into the bloodstream
Describe the features of a villi that make them efficient at absorption
They are thin walled (one cell thick) so that soluble products can pass through rapidly. They have a large surface area and a rich blood supply for absorption of glucose and amino acids. They also have a lacteal for absorption of fatty acids and glycerol
Name the structure that absorbs fatty acids and glycerol
Central lacteal (in the villi)
Name the structure that absorbs glucose and amino acids
Blood capillaries (in the villi)
Name five examples of lifestyle choices that can affect the transport system in humans
High fat diet, high salt diet, lack of exercise, use of tobacco, use of alcohol or stress
Name three examples of conditions that can arise if humans make poor lifestyle choices
Diabetes, heart attacks, strokes, fatty deposits in blood vessels, blood clots, unhealthy levels of stress
Describe the function of the small vein
It contains the xylem and phloem
Describe the function of the mesophyll
Layers of green cells which take in carbon dioxide during photosynthesis
Describe the function of the stomata
Pores in the lower leaf which allow entry of carbon dioxide and exit of oxygen
Describe the function of guard cells
Pairs of cells which control the opening and closing of the stomata
Explain how water up the roots, stem and to the leaf
Water moves into the root hair cells by osmosis. Water then travels upwards in the xylem. Water then travels to the stomata in the leaf and evaporates out.
Describe how wind affects transpiration
It increases the rate of transpiration. The air outside of the stomata is constantly replaced with drier air.
Describe how humidity affects the rate of transpiration
It decreases the rate of transpiration. Lots of water vapour in the air, less water lost through the stomata
Describe the function of the capillaries
To exchange gases, nutrients and waste
Describe the function of the upper epidermis
It is a protective layer which lets light through
