B2 - Scaling up

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Explain why a cell's DNA is replicated during the cell cycle
When the cell divides during mitosis, the two new cells will contain identical DNA
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What is mitosis?
Mitosis is when a cell reproduces itself by splitting to form identical offspring
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What is differentiation?
Differentiation is the process by which a cell changes to become specialised for its job
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What is diffusion?
The net movement of particles from an area of higher concentration to an area of lower concentration
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What is active transport?
The movement of particles across a membrane against a concentration/from an area of lower to an area of higher concentration using ATP released during respiration
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Define osmosis
Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.
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A piece of carrot is placed in a solution of lower water potential than its cells. Suggest what will happen to the piece of carrot. Explain your answer
The piece of carrot will shrivel and become floppy. This is because the cells become flaccid/lose water as a result of osmosis.
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Calculate the surface area: volume ratio of a cube with sides measuring 5cm.
surface area = 5x5x6 = 150. Volume = 5x5x5 = 125cm Ratio = 150:125 = 6:5
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Explain why it is beneficial for an exchange surface to be just one cell thick
It means that substances only have to travel a short distance
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Give three ways that leaves are specialised to maximise the diffusion of oxygen and carbon dioxide.
Leaves are broad so there's a large surface area for diffusion. Leaves are thin which means gases only have to travel a short distance.
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How are plant roots adapted to be able to absorb lots of water and mineral ions from the soil?
Each branch of a plant's roots is covered in millions of root hair cells, which gives the plant a big surface area for absorbing water and mineral ions from the soil
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Which chamber of the heart pumps deoxygenated blood to the lungs?
The right ventricle
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Describe how veins are adapted to carry blood back to the heart
They have a big lumen to help the blood flow despite the low pressure and they have valves to keep the blood flowing in the right direction
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Explain how capillaries are adapted to their function
Networks of capillaries carry blood to every cell in the body to exchange substances with them. They have permeable walls, so that substances can easily diffuse in and out of them. Their walls are one cell thick, which increases the rate of diffusion
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Describe three ways in which red blood cells are adapted to carry oxygen
Red blood cells have a large surface area to volume ratio for absorbing oxygen. They don't have a nucleus, which allows more room for carrying oxygen. Contain haemoglobin, which can combine with oxygen in the lungs and release it in a body tissue
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Explain why there is continuous upward flow of water in plants
Water evaporates and diffuses from a plant's surface, creating a slight shortage of water in the leaf. This draws more water up from the rest of the plant through the xylem vessels to replace it. This means more water is drawn up from the roots
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Name the cells that control the size of stomata
guard cells
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Explain how light intensity affects the rate of transpiration
In low light conditions, the stomata begin to close. This means that very little water can escape and the rate of transpiration decreases.
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Explain how temperature affects the rate of transpiration
As it gets warmer, the rate of transpiration increases because when it's warm the water particles have more energy to evaporate and diffuse out of the stomata
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Give two variables you should keep constant if investigating the effect of temperature on transpiration rate
Air humidity, light intensity, air movement
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Briefly describe the stages involved in the cell cycle
Cell grows and new cell sructures and proteins are made. Cell replicates it's DNA and splits ceating two cells with identical DNA. Cell keeps growing and proteins needed for cell division are made.
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Explan why the cells produced during mitosis are genetically identical
Because before the cell divides, the DNA forms chromosomes and each 'arm' of the chromosome is an exact copy of the other.
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Give an example of a cell that is specialised to carry out a particular function
A sperm cell or a palisade leaf cells
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Give two differences between embryonic stem cells and adult stem cells in animals
Embryonic stem cells can turn into any kind of cell and they are found in early human embryos. Whereas, adult stem cells are only found in certain places like bone marrow and cannot turn into any kid of cell only the tissue it has come from
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Where are stem cells found in plants?
roots and shoots
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Give three substances that move across cell membranes by diffusion
Glucose, amino acids, water, oxygen
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Explain how active transport is different from diffusion
Diffusion is a movement of particles from an area of higher concentration to an area of lower concentration. Whereas active transport is the movement f particles from an area of lower to an an area of higher concentration
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What is a partially permeable membrane?
A partially permeable membrane is a membrane with very small holes in it that only tiny molecules can pass through.
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Liquid A and liquid B are seperated by a partially permeable membrane. There is a net movement of water from liquid B into liquid A. Which liquid has the highest water potential?
Liquid B
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Give three factors that affect the movement of substances
Surface area to volume ratio, temperature, concentration gradient
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Explain why single-celled organisms don't require specialised exchange surfaces and transport systems to exchange substances
Because they are only one cell big, substances can diffuse straight into and out of single-celled organsims across the cell membrane
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Give an example of a specialised exchange surface found in an animal and explain how it is adapted to maximise the exchange of substances
In the lungs , the alveoli are adapted by an enormous surface area, very thin walls, a moist lining for dissolving gases and a good blood supply
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Give two substances that a plant takes in via its root hairs
water and mineral ions
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True or False? Humans have a single respiratory system
False - a double circulatory system
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How many chambers does the human heart have?
Four
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Is blood in the pulmonery artery oxygenated or deoxygenated
Dexygenated blood
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Through which vessel does blood leave the left ventricle of the heart?
Arteries
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Which type of blood vessel carries blood at high pressure?
Arteries
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What is the role of plasma?
To carry everything that needs transporting around the body
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What is the role of red blood cells?
To carry oxygen around the body
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Explain what is meant by translocation
The movement of food substances (e.g. sugars) around the plant
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Which type of plant transport vessel contains sieve tube elements?
Phloem tubes
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What is carried by xylem tubes?
Water and minerals
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Which type of plant transport vessel is made up of dead cells?
Xylem tubes
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Give three factors that affect the rate of transpiration
An increase in light intensity, an increase in temperature, an increase in air movement
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Where can most stomata be found?
On the lower surface of a leaf where it's darker and cooler
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Other cards in this set

Card 2

Front

What is mitosis?

Back

Mitosis is when a cell reproduces itself by splitting to form identical offspring

Card 3

Front

What is differentiation?

Back

Preview of the front of card 3

Card 4

Front

What is diffusion?

Back

Preview of the front of card 4

Card 5

Front

What is active transport?

Back

Preview of the front of card 5
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