X Topic 1 - Cell Biology

Question 1

What are all living things made of?

Answer 1

Cells.

Question 2

What are the two types of cells?

Answer 2

Eukaryotic (animal and plant) and prokaryotic (bacteria)

Question 3

What are eukaryotic cells?

Answer 3

Eukaryotic cells are complex and include all animal and plant cells.

Question 4

What are eukaryotes organisms made up of?

Answer 4

Eukaryotic cells.

Question 5

What are prokaryotic cells?

Answer 5

Prokaryotic cells are smaller and simpler than eukaryotic cells, e.g. bacteria.

Question 6

What is a prokaryote?

Answer 6

It is a prokaryotic cell (it’s a single-celled organisms).

Question 7

What are the different parts of a cell called?

Answer 7

Subcellular structures.

Question 8

What is a nucleus?

Answer 8

It contains genetic material that controls the activities of the cell/.

Question 9

What is the cytoplasm?

Answer 9

It is a gel-like substance where most of the chemical reactions happen. It contains enzymes that controls these chemical reactions.

Question 10

What is the cell membrane?

Answer 10

It holds the cell together and controls what goes in and out.

Question 11

What are the mitochondria?

Answer 11

They are where most of the reactions for aerobic respiration take place. Respirations transfer energy that the cell need to work.

Question 12

What are ribosomes?

Answer 12

They are where proteins are made in the cell.

Question 13

What is the subcellular structures for animal cells?

Answer 13

They contain a nucleus, the cytoplasm, a cell membrane, the mitochondria and the ribosomes.

Question 14

What is a rigid cell wall?

Answer 14

It is made of cellulose and it supports the cell and strengthens it.

Question 15

What does the permanent vacuole contains?

Answer 15

It contains the cell sap, a weak solution of sugar and salts.

Question 16

What are the chloroplasts?

Answer 16

Chloroplasts are where the photosynthesis occurs, which makes food or the plant. They contain a green substance called chlorophyll, which absorbs the light needed for photosyntheses.

Question 17

What is the subcellular structure of plant cells?

Answer 17

They contain all the bits that animal cells have and a rigid cell wall, a permanent vacuole and chloroplasts.

Question 18

What are plasmids?

Answer 18

They are small rings of DNA.

Question 19

What is the subcellular structure of a bacteria?

Answer 19

It contains a cell membrane, a cell wall, cytoplasm, plasmids and a single circular strand of DNA.

Question 20

Where does bacteria cells contains its genetic material (DNA)?

Answer 20

Bacteria cells don’t have a ‘true’ nucleus - instead they have a single circular strand of DNA that floats freely in the cytoplasm.

Question 21

What are the differences between eukaryotic cells and prokaryotic cells?

Answer 21

Prokaryotic cells are much smaller than eukaryotic cells. Eukaryotic cells contain membrane bound-organelles and a nucleus containing genetic material, while prokaryotic do not.

Question 22

How are cells studied?

Answer 22

By using microscopes.

Question 23

What are microscopes?

Answer 23

They let us see things that we can’t see with the naked eye.

Question 24

What is the meaning of magnify?

Answer 24

To make it look bigger.

Question 25

What does light microscopes do?

Answer 25

They use light and lenses to form an image of a specimen and magnify it. They let us see individual cells and large subcellular structures, like nuclei.

Question 26

What does electron microscopes do?

Answer 26

They use electrons instead of light to form an image. They have a much higher magnification than light microscopes. They have a higher resolution. They let us see much smaller things in more detail, like the internal structure of mitochondria and chloroplasts. They even let us see tinier things like ribosomes and plasmids.

Question 27

What is the meaning of resolution?

Answer 27

Resolution is the ability to distinguish between two points, so a higher resolution gives a sharper image.

Question 28

What is the formula for magnification?

Answer 28

Magnification = image size ÷ real size.

Question 29

What are the needed units and its standard forms?

Answer 29

Centimetre (cm) = x10‾²
Millimetre (mm) = x10‾³
Micrometre (µm) = x10‾⁶
Nanometre (nm) = x10‾⁹

Question 30

How to prepare a slide to view an onion cells?

Answer 30

1. Add a drop of water to the middle of a clean slide.
2. Cut up an onion and separate it out into layers. Use tweezers to peel off some epidermal tissue from the bottom of one f the layers.
3. Using the tweezers, place the epidermal tissue into the water on the slide.
4. Add a drop of iodine solution. Iodine solution is a stain. Satins are used to highlight objects in a cell by adding colour to them.
5. Place a cover slip (a square o thin, transparent plastic or glass) on top. To do this, stand the cover slip upright on the slide, next to the water droplet. Then carefully tilt and lower it s it covers the specimen. Try not to get any air bubbles under there - they’ll obstruct your view of the specimen.

Question 31

How to use a light microscope to look at a slide?

Answer 31

1. Clip the slide you’ve prepared onto the stage.
2. Select the lowest-powered objective lens.
3. Use the coarse adjustment knob move the stage up to just below the objective lens.
4. Look down the eyepiece. Use the coarse adjustment knob, until you get a clear image of what’s on the slide.
5. Adjust the focus with the fine adjustment knob, until you get a clear image of what’s on the slide.
6. If you need to see the slide with greater magnification, swap to a higher-powered objective lens and refocus.

Question 32

What is differentiation?

Answer 32

It is the process by which a cell changes to become specialised for its job.

Question 33

What happens as cells changes?

Answer 33

They develop different subcellular structures and turn into different types of cells. This allows them to carry out specific functions.

Question 34

When differentiation occurs?

Answer 34

It occurs as an organism develops. In most animal cells, the ability to differentiate is then lost at an early stage, after they become specialised. However, lots of plant cells don’t ever lose this ability.

Question 35

What are the cells that differentiate in mature animals used for?

Answer 35

They are used for repairing and replacing cells, such as skin or blood cells.

Question 36

What are stem cells?

Answer 36

They are undifferentiated cells.

Question 37

What are sperm cells specialised for and what is its function?

Answer 37

They are specialised for reproduction. The function of a sperm is basically to get the male DNA to the female DNA. It has a long tail and a streamlined head to help it swim to the egg. There are a lot of mitochondria in the cell to provide the cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.

Question 38

What are nerve cells specialised for and what is its function?

Answer 38

They are specialised for rapid signalling. The function of nerve cells is to carry electrical signal from one part of the body to another. These cells are long (to cover more distance) and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.

Question 39

What are muscle cells specialised for and what is its function?

Answer 39

They are specialised for contraction. The function of a muscle cell is to contract quickly. These cells are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction.

Question 40

What are root hair cells specialised for and what is its function?

Answer 40

They are specialised for absorbing water and minerals. Root hair cells are ells on the surface of plant roots, which grow into long “hairs” that stich out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil.

Question 41

What are phloem and xylem cells specialised for and what is its function?

Answer 41

They are specialised for transporting substances. Phloem and xylem forms phloem and xylem tubes, which transport substances such as food and water around plants. To form the tubes, the cells are long and joined end to end. Xylem cells are hollow in the centre and phloem calls have very few subcellular structures, so that stuff can flow through them.

Question 42

What does chromosomes contains?

Answer 42

They contain genetic information. This genetic material is contained in the nucleus in form of chromossomes.

Question 43

What are chromosomes?

Answer 43

Chromosomes are coiled up lengths of DNA molecules.

Question 44

What are genes and where are they carried?

Answer 44

Each chromosome carriers a large amount of genes. Different genes control the development of different characteristics such as hair colour.

Question 45

How many copies of each chromosome body cells normally have?

Answer 45

Two copies. One from the organisms ‘mother’, and one from its ‘father’. So humans have two copies f chromosomes 1, two copies of chromosome 2, etc.

Question 46

What happens to a body cell in multicellular organisms?

Answer 46

They divide to produce new cells as part of a series of stages called the cell cycle.

Question 47

What is mitosis?

Answer 47

It is the stage of the cell cycle when the cell divides.

Question 48

What does multicellular organisms uses mitosis for?

Answer 48

To grow or replace cells that have been damaged.

Question 49

What does the end of a cell cycle results in?

Answer 49

It results in two new cells identical to the original cell, with the same number of chromosomes.

Question 50

What are the main stages of the cell cycle in growth & DNA replication?

Answer 50

1. In a cell that’s not dividing, the DNA is all spread out in long strings.
2. Before it divides, the cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes.
3. It then duplicates its DNA - so there’s one copy for each new cell. The DNA is copied and forms X-shaped chromosomes. Each ‘arm’ of the chromosome is an exact duplicate of the other.

Question 51

What are the main stages of the cell cycle in mitosis?

Answer 51

Once its content and DNA have been copied, the cell is ready for mitosis.
4. The chromosomes line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosomes go to opposite ends of the cell.
5. Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells - the nucleus has divided.
6. Lately, the cytoplasm and cell membrane divide.
The cell has now produced two new daughter cells. the daughter cells contain exactly the same DNA - they’re identical. Their DNA is also identical to the parent cell.

Question 52

What can undifferentiated cells do?

Answer 52

Also known as stem cells, they can divide to produce lots more undifferentiated cells. They can differentiate into different types of cell, depending on what instructions they’re given.

Question 53

Where are stem cells found and why are they exciting to doctors and medical researches?

Answer 53

Stem cells are found in early human embryos. They’re exciting to doctors and medical researches because they have the potential to turn into any kind of cell at all. This makes sense if you think about it - all the different types of cell found in human being have to come from those few cells in the early embryo.

Question 54

Where are adults stem cells found?

Answer 54

In certain places like bone marrow.

Question 55

What can embryonic stem cells turn into?

Answer 55

They can only turn into certain cells such as blood cells but they can’t turn into any cell type at all.

Question 56

Where can stem cells from embryos and bone marrow be grown?

Answer 56

They can be grown in a lab to produce clones (genetically identical cells) and made to differentiate into specialised cells to use in medicine or research.

Question 57

What has medicine used adult stem cells for? Give an example.

Answer 57

To cure diseases. For example, stem cells transferred from the bone marrow of a healthy person can replace faulty blood cells in the patient who receives them.

Question 58

How can embryonic stem cells help sick people?

Answer 58

They could be used to replace faulty cells in sick people.

Question 59

How can embryonic stem cells help people with diabetes?

Answer 59

Insulin-producing cells could help people with diabetes.

Question 60

What type of embryonic stem cells can help people with paralysed by spinal injuries?

Answer 60

Nerve cells.