1 1 cell structure

A eukaryotic organism is an organism with cells that contain membrane-bound organelles, including a nucleus.

True. Plant and animal cells contain membrane-bound organelles, e.g. a nucleus and mitochondria, so they are eukaryotic cells.

The cell membrane separates cells from their surrounding environment.

The largest organelle within animal cells is the nucleus.

Plant cells contain the following structures that are not present in animal cells:

True. Ribosomes are present in plant and animal cells. They are the site of protein synthesis.

Organelles present within animal cells include: Note that structures such as the cell membrane and cytoplasm are not organelles, so are not acceptable answers here.

Ribosomes are the smallest organelle; they are present in both plant and animal cells.

False. The gel-like fluid present in plant and animal cells is the cytoplasm. Chloroplasts are organelles found in plant cells.

False. The role of the nucleus is to store genetic information in the form of DNA. Energy is released by the mitochondria.

Chloroplasts absorb light energy during the process of photosynthesis.

False. Plant cell walls provide strength and additional structural support for plant cells. It is the membrane that regulates the passage of substances.

The permanent vacuole stores cell sap and provides structural support for plant cells.

True. Mitochondria are responsible for releasing energy through the process of aerobic respiration.

A prokaryotic organism is a single-celled organism that lacks a nucleus and other membrane-bound organelles.

A plasmid is a small circular loop of DNA found in prokaryotic cells.

False. Bacteria lack a nucleus but contain a circular chromosome of DNA.

Bacterial cells have the following features: They lack mitochondria, a nucleus and other membrane-bound organelles.

False. Bacteria do not contain any internal membrane-bound structures, so do not have chloroplasts.

Flagella are thin, whip-like structures attached to bacteria that allow them to move.

Specialised cells are cells that have developed specific characteristics that allow them to perform particular functions.

Examples of specialised animal cells include: Other examples include red blood cells, nerve cells and muscle cells

False. Sperm cells contain half the amount of DNA compared to normal body cells. In humans this is 23 chromosomes.

Sperm cells are adapted to their function as follows:

An egg cell is adapted to its function as follows:

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).

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.

An electron microscope is an instrument that uses electron beams instead of light to provide higher resolution and magnification than light microscopes.

Electron microscopes allow scientists to view cells and organelles more clearly, and to see the structures inside cells.

A light microscope is an instrument that uses light and lenses to magnify specimens, allowing the visualisation of cells and large subcellular structures.

A microscope slide is a thin, flat piece of glass on which specimens are prepared for observation under a microscope.

True. Iodine solution can be used to stain onion cells.

Smudging the glass slide and trapping air bubbles under the coverslip should be avoided when preparing a microscope slide.

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.

False. When viewing a specimen under a light microscope the low-power lens should always be used first.

Biological drawings should follow specific rules, e.g.:

The formula for calculating magnification is: magnification = image size ÷ actual size

False. Magnification does not have any units and is just written as, e.g. x10 or 5000x.

The equation for calculating the actual size of a specimen is: actual size = image size ÷ magnification

There are 1000 µm in a mm.

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

There are 1000 nm in a µm.

6 x 104 as a whole number is 60 000.

0.0005 as standard form is 5 x 10-4