From Big to Small Flashcards
What are organelles?
Small structures inside a cell’s cytoplasm which carry out functions (jobs) to keep the cell alive .
What is the function of the nucleus?
- Controls the activity of the cell by making proteins
- Contains chromosomes - strands of DNA which carry genes (each gene codes for a protein)
What is the function of ribosomes?
Synthesises (assembles) proteins from amino acids
What is the function of the vacuole?
Filled with a watery liquid called cell sap; stores dissolved sugars, mineral ions and other substances.
How do microscopes work?
Light is reflected off structures inside the sample (object on the slide). The lenses focus that light so that we ca see the object.
What does changing the objective lens on a microscope do?
By changing the objective lens, we change the magnification (how many times bigger the object is than in real life)
What are cells?
The smallest functional unit of life and contain a number of organelles (e.g nucleus). The cells in an organism are not all the same, there are many different types, each with a different job. Different types of cells are described as specialised.
What are tissues?
A group of similar cells which work together to carry out the same function (job). An example in humans is muscle tissue.
What are organs?
Organs are made up of several different tissues working together to carry out a more complex function. In humans, muscle is one of the tissues making up the heart.
What are organ systems?
Organ systems are made up of several different organs working together to carry out a complex function essential to life e.g. circulating blood around the body).
What do all cells begin as?
Stem cells - these are not specialised to a particular job, but are able to divide over and over to make new cells.
What is used to test for sugars?
Benedict’s solution
How do you conduct a test for sugars?
- Add benedict’s solution to a sample of food
- Place in a water bath at 80°c for 5 minutes
- If sugar is present, the colour will change from blue to a brick red. If it turns green, yellow or orange, sugar is present but in a lower concentration
What is used to test for starch?
Iodine solution
How do you conduct a test for starch?
- Add a few drops of orange iodine solution to the sample on a spotting tile.
- If starch is present, the solution will turn into a blue-black colour
How do you conduct a test for protein?
- Add 2cm³ water to a food sample and shake (if not already liquid)
- Add an equal volume of dilute potassium hydroxide and shake
- Add 2 drops of 1% copper sulfate solution
- If protein is present the colour will change to a pale purple
What is used to test for protein?
Biuret
What is used to test for lipids?
- The food sample is placed in a test tube
- Add a small volume of absolute ethanol and shake to dissolve any lipid in the alcohol.
- Add an equal volume of water
- A cloudy white colour (Caused by emulsion forming) indicates the presence of lipids.
What is the function of the cell membrane?
Boundary between the cytoplasm and the cell’s surroundings. Controls what substances leave and enter the cell (selectively permeable)
What is the function of the Cytoplasm?
Jelly like liquid where chemical reactions occur.
What is the function of the mitochondria?
Carries out some reactions of aerobic respiration, producing ATP (energy carrier molecule)
What is the function of the chloroplast?
Absorb light energy and use it to carry out the reactions of photosynthesis, making biological molecules for plant cells
What is the function of the cell wall?
Made of cellulose (a carbohydrate) in plants. Helps to keep plants in a fixed shape (and so keeps the plant upright)
