63 terms

Year 9 KS4 Course: Biology

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What is a cell?
The smallest unit of a living thing
What features do animal and plant cells share?
Nucleus, cell membrane, cytoplasm, ribosomes, mitochondria
What features do plant cells have that animal cells do not have?
Chloroplasts, vacuole, cell wall
What is the function of the nucleus?
Contains DNA. Controls all the activities of the cell.
What is the cytoplasm and what is its function?
A liquid gel in which most of the chemical reactions needed for life take place
What is the function of the cell membrane?
Controls the passage of substances into and out of the cell
What is the function of the mitochondria?
Carry out respiration and provide energy for the cell
What is the function of the ribosomes?
To synthesise proteins for use by the cell
What is the cell wall made of?
Cellulose
What is the function of the cell wall?
Strengthens the cell and gives it support
What is the function of chloroplasts?
To generate glucose (food) for the cell through photosynthesis
Why are chloroplasts green?
They contain a chemical called chlorophyll which is green.
Which plant cells do not contain chloroplasts?
Root hair cells
What is the vacuole?
A space in the cytoplasm filled with cell sap
What is the function of the vacuole?
Keeps the cell rigid and supports the cell
What is a eukaryotic cell?
Cells with a membrane, cytoplasm and genetic material in a nucleus
Give two examples of eukaryotic cells
Plant and animal cells
What is a prokaryotic cell?
Cells with a cell wall that does not have cellulose and DNA in a loop which is free in the cytoplasm (not in a nucleus)
What type of cell are bacterial cells?
Prokaryotic
What is a plasmid?
An extra small ring of DNA found in a prokaryotic cell
What are flagella?
A whip-like tail that helps bacteria to move
What is the function of a nerve cell?
To transmit electrical impulses (messages) around the body
Why do nerve cells have dendrites?
To enable them to make connections to other nerve cells
What is name for the long section of a nerve cell?
The axon.
Why are nerve cells so long?
It helps them transmit messages around the body
Why do nerve cells have synapses?
For them to pass messages to other cells
How do nerve cells pass messages to other cells?
They use special transmitter chemicals
Why do nerve cells need lots of mitochondria?
To provide the energy needed to make the transmitter chemicals
What is the function of a striated muscle cell?
To contract and relax to move the body
What are the three main adaptations of striated muscle cells?
Special proteins, many mitochondria and glycogen storage
Why do striated muscle cells require special proteins?
To slide over each other and make the cell contract
Why do striated muscle cells require a lot of mitochondria?
To produce energy and help them contract and relax
What is glycogen?
A chemical that can be broken down and used by mitochondria to release energy
Where are sperm cells released from?
The testes which are far away from the egg they need to get to
What is the function of a sperm cell?
To carry genetic material from the male parent to the egg
Why do sperm cells have long tails?
To swim towards the egg
What is an acrosome?
A store of enzymes which break down the outer layers of the egg
Where are root hair cells found?
Close to the tips of growing roots
What is the function of a root hair cell?
To take up water and minerals for the plant
Why do root hair cells have a "root hair"?
To increase their surface area to make it easier to absorb water and minerals
What two other features do root hair cells have?
Many mitochondria, a large permanent vacuole
Why do root hair cells not have chloroplasts?
They do not photosynthesise
What is a photosynthetic cell?
A cell which specialises in photosynthesis
Where can photosynthetic cells be found?
In leaves and the outside of a plant's stem
What are the two main adaptations of photosynthetic cells?
Many chloroplasts and a large vacuole
What is xylem tissue?
Tissue which transports water and mineral ions from the roots to the top of the plant
Describe the structure of a xylem cell
Dead, hollow cells with spirals of lignin to support them
Why do xylem cells need to be strong?
To support the weight of the plant and withstand high pressure from water
What is phloem tissue?
Tissue that carries food from photosynthesis around a plant
Describe the structure of phloem cells
Lots of hollow tubes connected by sieve plates and surrounded by companion cells.
What is the function of the sieve plates?
To allow water containing dissolved food to move freely up and down the plant
Why do phloem cells require companion cells?
They have fewer internal structures like mitochondria so the companion cells keep them alive
What is diffusion?
The movement of particles from a region of high concentration to a region of low concentration
What is the rate of diffusion?
The speed at which particles move from high concentration to low concentration
What four factors affect the rate of diffusion?
Surface area, temperature, concentration gradient, thickness of the membrane
How does surface area affect the rate of diffusion?
The greater the surface area, the greater the rate of diffusion
Give an example of a specialised cell with a large surface area
Root hair cell
Why does increasing the temperature increase the rate of diffusion?
The particles have more energy and so move faster
What is a concentration gradient?
The difference in concentrations between two regions
How does concentration gradient affect rate of diffusion?
The greater the concentration gradient the greater the rate of diffusion
What is osmosis?
The movement of water across a cell membrane from a concentrated solution to a dilute solution
What is active transport?
A process of moving particles against a concentration gradient (from an area of low concentration to an area of high concentration)
Give an example of a cell which uses active transport
Root hair cell