Chapter B1- Cell Structure And Transport Flashcards
How do you calculate magnification?
Size of image/size of real object
What is the resolution on a microscope?
The ability to distinguish between two separate points
Explain the basic animal cell structure and the function of each of its structures
The nucleus- controls the activity of the cell
The cytoplasm- a liquid gel where most chemical reactions needed for life take place
The cell membrane- controls the passage and movement of substances such as urea, glucose, and hormones in and out of the cell
The mitochondria- structures within the cytoplasm where aerobic respiration take place, releasing energy for the cell
The ribosomes- where protein synthesis takes place, making all the proteins needed in the cell
Explain the basic plant cell structure and the function of each of its structures
The nucleus- controls the activity of the cell
The cell wall- strengthens the cell and gives it support
Chloroplasts- contain chlorophyll and is where photosynthesis takes place
A permanent vacuole- a place in the cytoplasm filled with cell sap, this supports the plant and keeps it rigid
The cytoplasm- a liquid gel where most chemical reactions needed for life take place
The cell membrane- controls the passage and movement of substances such as urea, glucose, and hormones in and out of the cell
The mitochondria- structures within the cytoplasm where aerobic respiration take place, releasing energy for the cell
The ribosomes- where protein synthesis takes place, making all the proteins needed in the cell
What is a eukaryote cell?
Have a cell membrane, cytoplasm and genetic material (DNA) enclosed in a nucleus
What is a prokaryote cell?
Has a cytoplasm surrounded by a cell membrane and a cell wall that does not contain cellulose. Has DNA that is not enclosed within a nucleus and is instead free within the cytoplasm.
Sometimes there are one or more small rings of DNA- what are they called?
Plasmids
Give an example of a prokaryote
Bacteria
Some bacteria have a long protein strand that lashes out in order for the cell to move- what is this called?
Flagella (singular)
Flagellum (plural)
What is differentiation/ specialisation?
The process where cells specialise to carry out a particular function
Give an example of a specialised cell that works individually?
Egg cell
Sperm cell
Give an example of a specialised cell that works as part of a tissue, and organ or a whole organism
Nerve cells
Root hair cells
Muscle cells
What do nerve cells do?
Nerve cells are specialised to carry electrical impulses around the body of an animal. This provides a rapid communication system between different parts of the body.
What is an adaptation of a nerve cell?
- Lots of dendrites to make connections with other cells
- An axon that carries the nerve impulse from one place to another.
- the nerve endings of synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals
What do muscle cells do?
Muscle cells are specialised cells that contract and relax in pairs to move the bones of the skeleton.
What is an adaptation of a muscle cell?
- They contain special proteins that slide over each other making the fibres contract
- They contain many mitochondria to transfer the energy needed for the chemical reactions that take place as the cells contract and relax
- They can store glycogen- a chemical that can be broken down and used in cellular respiration by the mitochondria to transfer the energy needed for the fibres to contract
What does a sperm cell do?
Sperm cells contain the DNA of the male counterpart during the process or fertilisation- when thy reach a female egg they can create life
What is an adaptation of a sperm cell?
- A long tail that whips from side to side to help move the sperm through water or the female reproduction system
- The middle section is full of mitochondria, which transfer the energy needed for the tail to swim
- The acrosome stores digestive enzymes for breaking down the outer layer of the egg
- A large nucleus contains the DNA to be passed on
Can plant cells specialise?
Yes
What does a root hair cell do?
Helps the plant to take up water and dissolves mineral ions through the roots of the plant.
What is adaptation of a root hair cell?
- They greatly increase the surface area available for water to move into the cell
- They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell
- They have many mitochondria that transfer the energy needed for active transport of mineral irons into the root hair cells
What does a photosynthetic cell do?
Photosynthetic cells carry out photosynthesis in order to make their own food to gain energy
What is an adaptation of a photosynthetic cell?
- Has chloroplasts containing chlorophyll that traps the light needed for photosynthesis
- They are positioned in continuous layers in the leaves and outer layers of the stem to achieve optimal absorption of light
- They have a large permanent vacuole that keeps the cell rigid as a result of osmosis. When lots of these rigid cells are arranged together they form a photosynthetic tissue that helps support the stem. They also keep the leaf spread out so it can capture as much light as possible
What does a xylem cell do?
Xylem is the transport tissue implants that carries water and mineral irons from the roots to the leaves of the plant. The xylem also supports the plant.
What is an adaptation of a xylem cell?
- Initially xylem cells are alive however a special chemical called lignin builds up in the cell walls. This kills the xylem cells. They then form long, hollow tubes that allow water and mineral irons to move easily through them
- The spirals and rings of lignin in the xylem cells make them very strong and help them withstand the pressure of water moving up the plant
What does a Phloem cell do?
Phloem is the specialised transport tissue that carries the food made by photosynthesis around the body of the plant. They are similar to xylem cells however they do not become lignified and die
What are the adaptations of phloem cells?
The cell walls between the cells breakdown to form special sieve plates. These allow water carrying dissolved food to move freely up and down the tubes to where it is needed.
- Phloem cells are supported by companion cells that help to keep them alive the mitochondria of the companion cells transfer the energy needed to move dissolved food up and down the plant in phloem
What is diffusion?
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
If there is only a small difference in concentration between two areas how quickly will diffusion occur?
The net movement by diffusion will be quite slow
How do you calculate net movement?
Particle moving in-particles moving out
What does temperature do to the rate of diffusion?
An increase in temperature means the particles in a gas or solution move around more quickly. When this happens diffusion takes place more rapidly as the random movement of the particles speeds up.
What is osmosis?
Osmosis is the diffusion of water through a partially permeable membrane from a dilute solution (with a high concentration of water) to a concentrated solution (with a low concentration of water) down a concentration gradient.
Define isotonic
If the concentration of solutes in the solution outside the cell is the same as the internal concentration, the solution is isotonic to the cell.
Define hypotonic
If the concentration of solutes in the solution outside of the cell is lower than the internal concentration, the solution is hypotonic to the cell.
Define hypertonic
If the concentration of solutes in the solution outside the cell is higher than the internal concentration, the solution is hypertonic to the cell
If an animal cell becomes hypotonic, what happens to the cell?
It will swell up and burst
If an animal cell becomes hypertonic, what happens to the cell?
It will shrivel up and can no longer survive
Why do plants rely on osmosis?
- To support their stems and leaves- water moves into plant cells by osmosis. This causes the vacuole to swell, which presses the cytoplasm against the plant cell wall. The pressure builds up until there is no more water that can physically enter the cell- this pressure is known as turgor. Turgor pressure makes the cell rigid and hard, which in turn keeps the leaves and stems of the plant rigid and firm.
- Plants also always need the fluid surrounding their cells to be hypotonic to the cytoplasm.
What is active transport?
The movement of substances from a dilute solution to a more concentrated solution against a concentration gradient, requiring energy from respiration
As living organisms get bigger, what happens to their volume ratio?
It gets smaller
What are some adaptations for exchanging materials (diffusion, osmosis, active transport)?
- Having a large surface area over which exchange can take place
- Having a thin membrane or being thin to provide a short diffusion pathway
- In animals, having an efficient blood supply moves the diffusing substances away from the exchange surfaces and maintains a steep concentration gradient
- in animals, being ventilated (movement of air and water into and out of the gas exchange organs) makes gas exchange more efficient by maintaining steep concentration gradients
What is the centre of a microscope called and what does it do?
The stage
Where you place the slide - has clips to hold it in place
What is below the stage and what does it do?
The lamp
Provides light for the slide
What is an adaptation of microscopes lamps?
Mirror to reflect natural light
What is above the stage and what does it do?
Objective lenses- magnifies
What is at the top of the microscope?
The eye piece- where you look into microscope
What does the course focusing dial do?
Positions objective lense so it almost touches microscope slide
Used to put cells into focus
What does the fine focusing dial do?
Brings cells into focus
Calculate magnification from microscope?
Eyepiece lenses times objectI’ve lense
