Topic 1 Flashcards
(34 cards)
What is a eukaryotic cell? (1 mark)
A complex cell which makes up all of plant and animal cells
What is a prokaryotic cell? (1 mark)
A small and simple cell, such as bacteria
True or false: all living things are made up of cells (1 mark)
True
True or false: single celled organisms are eukaryotes (1 mark)
False
What are the 5 msubcellular structures in an animal cell? (5 marks)
Nucleus - which contains genetic material
Cytoplasm - gel-like substance where most of the chemical reactions happen, with enzymes controlling these reactions
Cell membrane - holds the cell together, controls what goes in and out
Mitochondria - the POWERHOUSE OF THE CELL where aerobic respiration takes place, transferring energy that the cell needs to work
Ribosomes - where proteins are made in the cell
What the 3 subcellular structures in plant cells? (3 marks)
Rigid cell wall - made of cellulose, supports the cell and strengthens it
Permanent vacuole - contains cell sap
Chloroplasts - where photosynthesis occurs, contains chlorophyll which absorbs light for photosynthesis
What is cell sap? (1 mark)
A weak solution of sugars and salts
True or false: bacteria have a nucleus (1 mark)
False. They instead have a single DNA strang that floats freely in the cytoplasm
Give two differences between prokaryotic and eukaryotic cells (2 marks)
Any from:
Prokaryotic cells don’t have mitochondria but eukaryotic cells do
Eukaryotic cells have a real nucleus, prokaryotic cells don’t
Prokaryotic habe circular DNA but eukaryotic cells don’t
Prokaryotic cells are smaller than eukaryotic cells
What are microscopes used for? (1 marks)
To magnify iamges too small for the naked eye to see
Describe 3 ways that electron microscopes are different to light microscopes (3 marks)
Light microscopes use light and lenses to form the image, whereas electron microscopes use electrons to form the image
Electron microscopes have much higher magnification power and resolution than light microscopes
Electron microscopes let us see smaller things in more detail (e.g. internal structures of mitochondria), but light microscopes can only see individual cells and larger subcellular structures (e.g. nuclei)
What is the formula for magnification? (3 marks)
Magnification= image size/real size
A specimen is 50µm wide. Calculate the width of the image of the specimen under a magnification of x100. Give your answer in mm (3 marks)
image size = 100x50
image size = 5000µm
image size = 5mm
An onion cell is viewed under a microscope with x100 magnification. The image of the cell is 7.5mm wide. What is the real width of the onion cell? Give your answer in µm. (2 marks)
real size = magnification/imagesize
real size = 100/7.5mm
real size = 0.075
real size = 75µm
How do you prepare a slide? (5 marks)
- Add a drop of water to the middle of the slide
- Cut up an onion and separate it out into layers using tweezers to peel away the epidermal tissues from the bottom
- Using the tweezers, place the epidermal tissue into the water on the slide
- Add a drop of iodine solution to stain the highlighted objects in a cell with colour
- Standing the slip upright, place a cover over the slip. Try not to get bubbles under the clip as they can obstuct your view of the specimen
How do you set up a microscope to look at a slide? (6 marks)
- Clip the slide onto the stage
- Select the least magnified objective lens
- Use the coarse adjustment knob to move the stage just below the lens
- Look down the eyepiece and use the focus knob to change the focus so you can roughl see the magnified image
- Adjust the fine adjustment knob until the image is clear
- If you need a more magnified image, selected a different objective lens to fit your requirements.
Name five things you should always do whilst drawing your observations (5 marks)
Any from:
Drawing takes up half the page
Neat/sharpened pencil
No colour or shading
Drawn in proportion
Remember a title
Label important parts of the drawing
Why might you add stain to the sample on a microscope slide? (1 mark)
To highlight the objects in the sample by giving them colour
When do most cells differentiate? (1 mark)
As an organism develops
Do cells lose the ability to differentiate at an early stage? (2 marks)
In most animals cells, the ability to differentiate is lost very early. However, in most plant cells it is never lost.
Name 5 specialised cells and how they are specialised (5 marks)
Sperms cells: has a long tail and streamlined head to get to the female eggs easier
Nerve cells: branched connections at their ends to connect to other nerve cells and form a network throughout the body. This makes rapid signalling easier
Muscle cells: long with space to contract, containing lots of mitochondria (the powerhouse of the cell) to generate enery quicker to contraction
Root hair cells: long hairs that stick out into the soil. This gives that plant a big surface area to absorb water and mineral ions from the soil
Phloem and Xylem cells: Xylem cells are hollow in the centre and Phloem cells have very few subcellular structures, making it easier to transport substances through their tubes
Plants transport food substances from the leabes to growing parts of the plant through phloem tubes. Give one feature of a phloem cell that makes it specialised for its function (1 mark)
They are joined end-to-end
Describe how a root hair cell is specialised for its function (2 marks)
They have long hairs that stick out into the soil and a big surface area
Explain what chromosomes are and how they work (4 marks)
Chromosomes are coiled up strands of DNA stored within the nucleus. They each carry a large number of genes, controlling different characteristics such as hair long. There are usually two of each gene, one from your mother and one from your father
