What are eukaryotic organisms?
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What are eukaryotic organisms?
A eukaryotic organism is an organism with cells that contain membrane-bound organelles, including a nucleus.
True or False?
Plants and animal cells are eukaryotic.
True.
Plant and animal cells contain membrane-bound organelles, e.g. a nucleus and mitochondria, so they are eukaryotic cells.
What separates cells from their surrounding environment?
The cell membrane separates cells from their surrounding environment.
Name the largest organelle present within animal cells.
The largest organelle within animal cells is the nucleus.
Name the structures present in plant cells that are not present in animal cells.
Plant cells contain the following structures that are not present in animal cells:
cell wall
chloroplasts
permanent vacuole
True or False?
Ribosomes are present in both plant and animal cells.
True.
Ribosomes are present in plant and animal cells. They are the site of protein synthesis.
Name three organelles found within animal cells.
Organelles present within animal cells include:
nucleus
mitochondria
ribosomes
Note that structures such as the cell membrane and cytoplasm are not organelles, so are not acceptable answers here.
What is the smallest organelle present in both plant and animal cells?
Ribosomes are the smallest organelle; they are present in both plant and animal cells.
True or False?
The gel-like fluid present inside both plant and animal cells is the chloroplast.
False.
The gel-like fluid present in plant and animal cells is the cytoplasm. Chloroplasts are organelles found in plant cells.
True or False?
The role of the nucleus is to release energy for the cell.
False.
The role of the nucleus is to store genetic information in the form of DNA. Energy is released by the mitochondria.
What is the function of chloroplasts within plant cells?
Chloroplasts absorb light energy during the process of photosynthesis.
True or False?
Plant cell walls control the passage of substances in and out of cells.
False.
Plant cell walls provide strength and additional structural support for plant cells. It is the membrane that regulates the passage of substances.
What is the function of the permanent vacuole in plant cells?
The permanent vacuole stores cell sap and provides structural support for plant cells.
True or False?
Mitochondria are the site of aerobic respiration.
True.
Mitochondria are responsible for releasing energy through the process of aerobic respiration.
What is a prokaryotic organism?
A prokaryotic organism is a single-celled organism that lacks a nucleus and other membrane-bound organelles.
Define the term plasmid.
A plasmid is a small circular loop of DNA found in prokaryotic cells.
True or False?
Bacteria have a nucleus.
False.
Bacteria lack a nucleus but contain a circular chromosome of DNA.
What are the features of bacterial cells?
Bacterial cells have the following features:
chromosomal DNA
cell membrane
ribosomes
plasmid DNA (some cells)
flagella (some cells)
cell wall
They lack mitochondria, a nucleus and other membrane-bound organelles.
True or False?
Bacteria contain chloroplasts.
False.
Bacteria do not contain any internal membrane-bound structures, so do not have chloroplasts.
What is the role of a flagellum (plural flagella)?
Flagella are thin, whip-like structures attached to bacteria that allow them to move.
Define the term specialised cell.
Specialised cells are cells that have developed specific characteristics that allow them to perform particular functions.
Give an example of a specialised animal cell.
Examples of specialised animal cells include:
sperm cells
egg cells
ciliated epithelial cells
Other examples include red blood cells, nerve cells and muscle cells
True or False?
Sperm cells contain a full set of chromosomes (46 in humans).
False.
Sperm cells contain half the amount of DNA compared to normal body cells. In humans this is 23 chromosomes.
How are sperm cells adapted to their function?
Sperm cells are adapted to their function as follows:
acrosome containing digestive enzymes to penetrate the egg cell
haploid nucleus containing half the number of chromosomes
mitochondria for energy release (through respiration) for swimming
tail to swim
How is an egg cell adapted to its function?
An egg cell is adapted to its function as follows:
nutrients in the cytoplasm for the growth of the early embryo
haploid nucleus containing half the number of chromosomes
changes in the cell membrane after fertilisation so that only one sperm can fertilise the egg nucleus
How are ciliated epithelial cells adapted to their function?
Ciliated epithelial cells are adapted to have hair-like extensions on their cell membrane. These waft/beat to move mucus (in the trachea) or an egg cell (in the oviducts).
True or False?
Upon the invention of the light microscope in the 17th century, scientists were able to view cell structure in detail.
False.
The first light microscopes to be invented allowed only very basic details of cell structure to be observed, such as cell shape and the plant cell walls.
What is an electron microscope?
An electron microscope is an instrument that uses electron beams instead of light to provide higher resolution and magnification than light microscopes.
What can be achieved using electron microscopes that could not be achieved prior to their invention?
Electron microscopes allow scientists to view cells and organelles more clearly, and to see the structures inside cells.
What is a light microscope?
A light microscope is an instrument that uses light and lenses to magnify specimens, allowing the visualisation of cells and large subcellular structures.
What is a microscope slide?
A microscope slide is a thin, flat piece of glass on which specimens are prepared for observation under a microscope.
True or False?
Iodine solution can be used to stain onion cells.
True.
Iodine solution can be used to stain onion cells.
What should be avoided when preparing a microscope slide?
Smudging the glass slide and trapping air bubbles under the coverslip should be avoided when preparing a microscope slide.
What is an objective lens on a microscope?
An objective lens is the lens on a microscope that is closest to the specimen. Most light microscopes have several objective lenses at different powers for viewing specimens at different levels of magnification.
True or False?
The highest-powered objective lens should always be used first when viewing a specimen under a light microscope.
False.
When viewing a specimen under a light microscope the low-power lens should always be used first.
What are the key characteristics of scientific drawings made from observations under the microscope?
Biological drawings should follow specific rules, e.g.:
use a sharp pencil
pencil lines should be clear and unbroken
all structures drawn should be in proportion
identifiable features must be labelled using straight, uncrossed lines
What is the formula for calculating magnification?
The formula for calculating magnification is:
magnification = image size ÷ actual size
True or False?
Magnification has units.
False.
Magnification does not have any units and is just written as, e.g. x10 or 5000x.
What is the equation for calculating the actual size of a specimen?
The equation for calculating the actual size of a specimen is:
actual size = image size ÷ magnification
How many µm are there in a mm?
There are 1000 µm in a mm.
True or False?
1.2 mm is the same as 12 000 µm.
False.
1.2 mm is not the same as 12 000 µm.
µm are converted into mm by multiplying by 1000, so:
1.2 x 1000 = 1200 µm
How many nm are in a µm?
There are 1000 nm in a µm.
What is 6 x 104 as a whole number?
6 x 104 as a whole number is 6000.
Convert 0.0005 into standard form.
0.0005 as standard form is 5 x 10-4