BTEC Applied science Unit 1

1665: Robert Hooke first described cells

1674 - 1683: The first living cell was observed

1831: Nucleus observed 

1674 - 1683: Universal cell theory

1852: Evidence for the origin of new cells

1860: Spontaneous generation disproved  

Eukaryotic cells make up multicellular organisms such as plants and animals. They are complex cells with a nucleus and membrane-bound organelles.

Prokaryotic cells are single-celled organisms. They are simple structures and do not have a nucleus or any membrane-bound organelles.

State two functions of the Golgi apparatus: sorting and packaging of proteins for secretion. It is also involved in the transport of lipids, and the creation of lysosomes.

Name as many animal cells as you can with there functions:

Nucleus: The organelle that contains the cells DNA and is the control centre of the cell.

Chloroplast: The organelle that uses the energy of sunlight to make food.

Endoplasmic reticulum: The organelle that makes lipids breaks down drugs and other substances, and packages proteins for Golgi complex.

mitochondrion: The organelle that breaks down food molecules to make ATP.

Ribosomes: The organelle in which amino acids are hooked together to make proteins.

Lysosomes: The organelle that digests food particles, wastes, cell parts, and foreign invaders.

Name a few organelles found in a plant cell that is not present in an animal cell.

ANSWER: Plant cells do not have lysosomes or centrosomes.The plant cell does, however, have a cell wall, chloroplasts, plastids, and a central vacuole

Name the type of ribosome found in bacteria.

ANSWER: Bacterial ribosomes are composed of two subunits with sedimentation rates of 50S and 30S, as opposed to 60S and 40S in eukaryotic cells.

Explain how the ultrastructure of a bacterium capsule prevents dehydration.

ANSWER: Many bacterial cells secrete some extracellular material in the form of a capsule or a slime layer. Most capsules are hydrophilic (“water-loving”) and may help the bacterium avoid desiccation (dehydration) by preventing water loss.

Briefly explain how to carry out gram staining using your own words.

ANSWER: 

1. Applying a primary stain (crystal violet) to a heat-fixed smear of a bacterial culture. ...
2. The addition of iodide, which binds to crystal violet and traps it in the cell.
3. Rapid decolourization with ethanol or acetone.
4. Counterstaining with safranin.

Explain how the mid-piece of a human sperm cell is specialised to support the function of its tail.

ANSWER: The mid-point contains many mitochondria to supply the movement 

(I) = Image size (A) = Actual size x (M) = Magnification

I= AM

M=I/A

A=I/M

A microbiologist measures an electron micrograph image of a bacterium to be 4.5 cm in length. The magnification used to view the bacterium was 22,500x. Calibrate the actual size of the bacterium.

ANSWER: 0.0002

Explain how the shape of red blood cells allows them to carry out their function

Red blood cells are a biconcave shape. This increases the surface to volume ratio of an erythrocyte. They are flexible so that they can squeeze through narrow blood capillaries. Their function is to transport oxygen around the body.

What is the function of neutrophils? 

Neutrophils are a type of white blood cell and they play an important role in the immune system. They have multi-lobed nuclei, which enables them to squeeze through small gaps when travelling to the site of infection.

What is the name of the lung tissue that contains ciliated cells?

A) columnar endothelium

B) columnar epithelium

C) Squamous endothelium

D) Squamous epithelium

ANSWER: B

Chemicals in cigarette smoke reduce the movement of the cilia on ciliated cells in the human lung. Explain how reducing the movement of this cilia can result in a smoker having to cough.

ANSWER: Because the cilia moves the mucus in the lungs