B2.1 - Supplying The Cell Flashcards

1
Q

What is diffusion?

A

The net movement of particles from a higher concentration to a lower concentration until they reach equilibrium.

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2
Q

Where does diffusion occur in the body?
And what is being diffused?

A

Between blood and the cells in your body
Diffuses glucose and oxygen into cells that need them

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3
Q

How do you increase the rate of diffusion?

A

Decrease the distance the particles need to move
Increase the concentration gradient
Increase the surface area

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4
Q

What is osmosis?

A

The special type of diffusion of water molecules across a selectively permeable cell membrane

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5
Q

What is water potential?

A

The concentration of free water molecules

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6
Q

What substance has the highest possible water potential?

A

Pure water

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7
Q

What is active transport?

A

Allows cells to move substances from an area of low concentration to high concentration against their concentration gradient

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8
Q

How can particles move against the concentration gradient in active transport?

A

Energy must be transferred from an energy store

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9
Q

What are the three key features of active transport?

A

Particles transported against concentration gradient
ATP required - comes from respiration
Makes use of carrier proteins in the cell membrane

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10
Q

How do cells adapt to carrying out active transport?

A

More mitochondria

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11
Q

What does the rate of active transport depend on?

A

Rate of respiration to produce the required ATP

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12
Q

What are carrier proteins?

A

Special proteins that span across the width of the cell membrane that can change shape or rotate to transport the molecule into the cell

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13
Q

What are some examples of active transport?

A

Digestion - glucose transferred into the bloodstream via the villi
Nerve cells - pumps sodium ions out and potassium ions in for creating nerve impulses
Root hair cells - taking in water and mineral ions

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14
Q

What is mitosis?

A

The process by which body cells divide to produce two identical daughter cells

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15
Q

Why do humans need mitosis?

A

It grows the cells we need to grow bigger and to replace the dead cells

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16
Q

What is the cell cycle?

A

The process of cell growth and division

17
Q

What are the four stages of the cell cycle?

A

DNA replication, movement of chromosomes, cytokinesis and the growth of the daughter cell

18
Q

Stage 1 of the cell cycle:
How is DNA replicated?

A

The DNA molecule unzips, forming two separate strands
Free nucleotides in the nucleus line up against each of the strands, forming base pairs
When the strand is complete, there are two identical molecules of DNA

19
Q

Stage 2 of the cell cycle:
How do the chromosomes move?

A

The chromosome line up across the centre of the cell
Two identical copies of each chromosome (formed when the DNA is replicated) separate and move to opposite ends of the cell. Each end has a full set of identical chromosomes
Two new nuclei form

20
Q

Stage 3 of the cell cycle:
What is cytokinesis?

A

Following the movement of chromosomes, the cell membrane pinches inwards to separate and enclose the two nuclei, and then pinches off to split the original cell into 2 new daughter cells, which will grow independently

21
Q

Stage 4 of the cell cycle:
What happens to the individual daughter cells?

A

They begin replicating their DNA, and they cell cycle continues

22
Q

What is special about stem cells?

A

They are undifferentiated cells, and they become specialised after being formed by mitosis. This means they can develop into any type of specialised cell, and help grow tissues and organs

23
Q

When are stem cells used by the body?

A

During development, growth and repair

24
Q

What are the two types of stem cell?

A

Embryonic and adult stem cells

25
Q

What is the function of embryonic stem cells?

A

Found in embryos where they divide by mitosis to produce all the cells needed to make an organism.
They have the ability to differentiate into all types of cells

26
Q

What is the function of adult stem cells?

A

Found in various body tissues, and they can differentiate into some cells, but not as many as embryonic cells

27
Q

Once an animal is fully grown, many adult stem cell remain in a non-dividing state for years. What can activate them?

A

Disease or tissue injury can activate the for mitosis

28
Q

What are the only parts of a plant that grow for the plant’s whole life?

A

Meristems