BIOLOGY B1 Flashcards
(48 cards)
What is the range of sizes with animal cells and plant cells?
- Animal cells are between 0.01 mm – 0.05 mm
- Plant cells are between 0.01 mm – 0.10 mm
The human eye can see objects as small as around 0.05 mm
Go onto BBC bitesize and learn the different parts of the microscope on the first slide.
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What is the equation for the magnification of the microscope?
Magnification of microscope = Magnification of eyepiece × magnification of objective.
What is the unit for the magnification of a lens?
Shown by a multiplication sign followed by the amount the lens magnifies. E.g. x10
What is the equation for the magnification of an image?
Magnification of an image = size of the image/real size of the object
What is a micrometer and a nanometer in standard form and as a fraction?
1 Micrometer = 1/1,000,000 metres,
1 Nanometer = 1/1,000,000,000 metres
What are some of the risks when preparing biological samples for examination?
- Care taken when looking down the microscope if the illumination is bright
- Care when using microscopic stains
- Careful when handling coverslips and needles
When was the first compound microscope made and who made it?
Dutch spectacle makers Janssen experimented with putting lenses in tubes. They made the first
compound microscope.
Which scientist constructed the first microscope that magnified up to x275?
Antonie van Leeuwenhoek in the late 1600s.
What are the two types of electron microscopes?
The scanning electron microscope - is used to examine the surface structure of specimens.
The transmission electron microscope - used to examine thin slices or sections of cells or
tissues.
What is the maximum magnification of an electron microscope and a light microscope?
Electron microscopes - around x 1,000,000
Light microscopes - around x 2,000
What are some of the differences light microscopes and electron microscopes? Pros and Cons.
- Light microscopes use visible light for imaging whereas electron microscopes use electron beams.
- An electron microscope has a higher resolution than a light microscope.
- An electron microscope has a stronger magnification compared to a light microscope
- Light microscopes have a deeper field than electron microscopes.
- Light microscopes can have larger sample sizes whereas electron microscopes are limited
- Electron microscopes are more expensive and there is limited availability.
- Electron microscopes require high vacuum conditions unlike the light microscopes which don’t.
- Electron microscopes have a slower observation speed
What do ribosomes do and which cell are they found in?
Tiny structures where protein synthesis occurs and they are found in animal cells.
What do the following parts of a cell do?
- Cytoplasm
- Nucleus
- Mitochondria
Cytoplasm - A jelly-like material that contains dissolved nutrients and salts and structures called organelles. It is where many of the chemical reactions happen.
Nucleus - Contains genetic material, including DNA, which controls the cell’s activities.
Mitochondria - Organelles that contain the enzymes for respiration, and where most energy is released in respiration.
What do the following parts of a cell do?
- Chloroplasts
- Cell wall
- Vacuole
Chloroplasts - Organelles that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis.
Cell Wall - Made from cellulose fibres and strengthens the cell and supports the plant.
Vacuole - Filled with cell sap to help keep the cell turgid.
How do you measure the size of a cell?
Length of cell = graticule divisions x 4.9, with an eyepiece graticule.
- Cells of bacteria are called
prokaryotic cells - Cells of animals, plants and fungi are called
eukaryotic cell
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What types of cell division is a eukaryotic and a prokaryotic cell in?
Eukaryotic - Mitosis
Prokaryotic - Binary fission
How large are prokaryotic and eukaryotic cells?
Prokaryotic = 0.2 - 2 micrometres
Eukaryotic = 5 - 100 micrometres
What adaption does a sperm cell and nerve cell have to help them carry out their functions?
Sperm cell - packed with mitochondria to release energy when needed to swim, the head of the sperm contains genetic material for fertilisation.
Nerve cell - extensions and branches help it to communicate with other nerve cells, it’s extended to allow nerves from all different parts of the body to go to the central nervous system
What adaptions does a root hair cell, a xylem cell and a phloem cell have in order for them to carry out their functions?
Root hair cell - Large surface area ensures contact with soil water, thin walls that don’t restrict the movement of water
Xylem cell - No top to bottom walls between vessels so there’s a continuous column of water running through them, thickened walls provide support for the plant.
Phloem - Dissolved sugars and amino acids can travel up and down the system, companion cells adjacent to sieve tubes provide energy required to transport substances.
What do chromosomes carry?
Genetic information in a molecule called DNA.
What does mitosis do?
Ensures that when a cell divides each new cell produced has the same genetic information.
How many chromosomes does each human body contain?
23 pairs - 46
