Multicellular organisms - Flashcards
What is transpiration?
The process of water moving through a plant and its evaporation through the stomata
What are the structures and processes involved as water moves through the plant from the soil to the air?
Water moves from the soil into the root hair by osmosis.
Water then moves by osmosis from the root hair cell to the xylem in the root.
Water then travels up the xylem in the stem.
Water then moves by osmosis from the xylem to the spongy mesophyll in the leaf.
Water then evaporates from the spongy mesophyll into the moist airspace inside the leaf.
Water vapour then moves by diffusion from the air space in the leaf out through the stomata into the air.
What can external factors do?
Increase or decrease the rate of transpiration. eg light intensity, temperature, wind speed, humidity
How does light affect the rate of transpiration?
In bright light transpiration increases, and the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis
How does temperature affect the rate of transpiration?
Transpiration is faster in higher temperatures, evaporation and diffusion are faster at higher temperatures
How does wind speed affect the rate of transpiration?
wind speed is faster in windy conditions, water vapour is removed quickly by air movement, speeding up diffusion of more water vapour out of the leaf.
How does humidity affect the rate of transpiration?
Transpiration is slower in humid conditions, diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air.
How does leaf surface area affect the rate of transpiration?
Higher leaf surface area leads to faster transpiration, a larger leaf has more stomata, so more water will be evaporating and diffusing away from the plant. Plants may lose leaves at times of water shortage to combat this.
In mammals what does the blood contain?
Plasma, red blood cells and white blood cells
What does blood transport?
Nutrients, oxygen and carbon dioxide.
How are red blood cells specialised to carry oxygen?
They are biconcave in shape, have no nucleus and contain haemoglobin
How do red blood cells transport oxygen efficiently?
In the form of oxyhaemoglobin
What is the chemical formula for the production of oxyhaemoglobin
oxygen+haemoglobin= oxyhaemoglobin
What are white blood cells part of and what are they involved in?
They are part of the immune system and they are involved in destroying pathogens.
What are pathogens?
Disease-causing micro-organisms.
What are the two main types of blood cells involved in destroying pathogens?
Phagocytes and lymphocytes
What do phagocytes do?
They carry out phagocytosis by engulfing pathogens.
Describe the process of phagocytosis
When a phagocyte detects a pathogen it captures it by flowing its cell membrane around the pathogen and engulfing it in a vacuole in its cytoplasm. The trapped pathogen is then digested using enzymes.
What do some lymphocytes do?
They produce antibodies which destroy pathogens.
What is each antibody specific to?
A particular pathogen.
Describe the sequence of events in mitosis.
Each chromosome makes an identical copy of itself- the two copies are called chromatids.
The chromatid pairs line up at the equator of the cell.
Spindle fibres now pull the pairs of chromatids apart so that only one copy of each chromosome moves to each pole of the cell.
Nuclear membrane forms around each set of chromosomes at the poles.
After the two nuclei have formed, the cytoplasm divides and 2 separate diploid cells are formed.
What is an equator?
the region in the middle of the cell where the chromatid pairs line up before they are separated
What are spindle fibres?
strands of protein that the cell uses to separate the chromatid pairs from the equator to the poles
What does mitosis provide and maintain?
provides new cells for growth and repair of damaged cells and maintains the diploid chromosome complement.
What are diploid cells?
Cells that have two matching sets of chromosomes, which are replicated during mitosis
What are stem cells?
unspecialised cells that can divide in order to self-renew
What do stem cells have the potential to do?
become different types of cell
What are stem cells involved in?
growth and repair
Where can stem cells be obtained from?
the embryo at a very early age
where can tissue cells be found?
in the body, throughout life
what are stem cells used for?
therapies such as bone marrow transplants. skin grafts and cornea repair.
What does the specialisation of cells lead to?
the formation of a variety of cells, tissues and organs.
Describe multicellular organisms
multicellular organisms have more than one cell type and are made up of tissues and organs.
What do organs do?
perform different functions
Describe cells in organs.
They are specialised for their functions.
What is the hierarchy that exists?
cells-tissues-organs-systems
Give an example of a specialised plant cell.
xylem vessel-hollow tube, wall strengthened by lignin-support and water transport
Give an example of a specialised animal cell.
cheek epithelium-flat irregular shape-protection of mouth lining
What can a response to a stimulus be?
a rapid action from a muscle or a slower response from a gland
What does the nervous system consist of?
the CNS and other nerves
What does the CNS consist of ?
brain and spinal cord
What is the cerebrum?
the large folded area of the brain and is responsible for conscious thoughts, reasoning, memory and emotions
what is the cerebellum?
found at the rear of the brain below the cerebrum and controls balance and coordinated movement
what is the medulla
the medulla is found at the top of the spinal cord and transmits electrical impulses to the heart and lungs to control heart rate and breath rate