4th Form Biology Autumn Term A

4th Form Biology

By what process do bacteria divide?

Binary fission.

Define excretion.

Excretion is the removal of waste products from an organism.

Define growth.

An increase in the size or number of cells.

Define homeostasis.

Homeostasis is the maintenance of constant internal conditions despite changes in the external environment.

Define organ.

A collection of several tissues working together.

Define respiration

Respiration is the release of energy through the from a molecule such as glucose.

Define sensitivity.

Sensitivity is the ability to respond to changes in the surroundings.

Define tissue.

A group of cells with similar function.

How do bacterial cells differ from Eukaryotic cells?

Peptidoglycan cell wall; no nucleus; DNA in the form of a loop; DNA not packaged around histone proteins; plasmids; no mitochondria/chloroplasts.

How is the permeability of cell walls described?

All cell walls are completely permeable to molecules.

How large is a typical bacterial cell?

1 - 2 μm

How many chromosomes does a typical human cell contain?

46 (23 pairs).

How many mm are in one μm?

0.001

In what two ways can an organism grow?

By enlarging cells by increasing the volume of cytoplasm. By cell division, which will increase the number of cells in the organism.

In which organelle does respiration take place?

Mitochondrion (plural mitochondria).

List four components of a typical animal cell.

Cell surface membrane; cytoplasm; nucleus; ribosomes; mitochondria.

List four components of a typical fungal cell.

Cell surface membrane; cytoplasm; nucleus; permanent vacuole; ribosomes; mitochondria; chitin cell wall.

List four components of a typical plant cell.

Cell surface membrane; cytoplasm; nucleus; ribosomes; mitochondria; chloroplast; permanent vacuole; cell wall.

Name two chemicals that humans excrete.

Carbon dioxide and urea.

Name two types of nucleic acid.

DNA and RNA.

State three requirements for bacteria to grow in the laboratory.

1. A suitable temperature. 2. Water. 3. Nutrients such as glucose.

What are the tenets of cell theory?

All organisms are made up of cells. The cell is the smallest unit of life. Cells can only be derived from pre-existing cells.

What is a bacterial colony?

A group of bacteria that have formed from one original bacterial cell.

What is a gene?

A section of DNA that codes for the production of a protein.

What is a pathogenic bacterium?

A disease-causing bacterium.

What is a Prokaryote?

A bacterial cell.

What is autotrophic nutrition?

Autotrophs synthesise their own organic food molecules from carbon dioxide.

What is chlorophyll?

The green pigment in chloroplasts that absorbs light energy.

What is egestion?

Egestion is the removal from the body of undigested food in the form of faeces.

What is fermentation?

Anaerobic respiration (without oxygen).

What is heterotrophic nutrition?

Heterotrophic organisms use pre-existing organic food molecules.

What is stored in a vacuole?

Water, mineral ions, sugars, pigments.

What is the cell surface membrane made of?

Lipids and protein.

What is the cell wall made of in (a) plants (b) fungi (c) bacteria?

(a) cellulose (b) chitin (c) peptidoglycan.

What is the difference between a Prokaryotic cell and a Eukaryotic cell?

Prokaryotes lack a membrane bound nucleus. Eukaryotes have DNA arranged into linear chromosomes.

What is the function of mitochondria?

Aerobic respiration occurs in mitochondria.

What is the function of the cytoplasm?

It is where biochemical reactions take place.

What is the liquid called in which bacterial are grown in a laboratory?

Nutrient broth.

What is the name of the bacterium that causes cholera?

Vibrio cholerae.

What is the name of the bacterium used to make yoghurt?

Lactobacillus.

What is the purpose of a plant cell wall?

It gives the cell its shape and prevents the cell from bursting.

What is the waste product of Lactobacillus?

Lactic acid.

What substances are found in the vacuole of plant cells?

Water, dissolved ions, dissolved sugars.

What term is used to describe the permeability of a cell surface membrane?

Selectively or partially permeable.

Where are proteins made in a cell?

On ribosomes.

Where does respiration occur in Eukaryotes?

In mitochondria.

Where does respiration take place in bacteria?

In the cytoplasm.

Which characteristic of life do viruses exhibit?

Reproduction.

Which components of a cell are found in all types of cell?

Cell membrane; cytoplasm; ribosomes.

Which four components do all cells possess?

Cell surface membrane; Cytoplasm; DNA; Ribosomes.

Which organisms are Prokaryotes?

Bacteria.

Which process occurs in chloroplasts?

Photosynthesis.

Which unit is most appropriate to measure the size of cells?

Micrometre (μm)

Why do organisms need to excrete waste products?

They may be toxic at high concentrations.

Why do you use aseptic technique when working with bacteria?

To avoid contaminating your experiment and to avoid contaminating you.

Why is working by a Bunsen burner part of aseptic technique?

It creates an updraft which will carry airborne bacteria up and away from your experiment.

Why is yoghurt thicker than milk?

The lactic acid lowers the pH which causes proteins to become insoluble.