Specialised Cells

Question 1

Muscle Cells

Answer 1

• muscle cells are adapted to contract
• they are shaped as long tubes
• muscle cells also contain a large number of mitochondria to provide energy

Question 2

Nerve Cells

Answer 2

• nerve cells are specialised to send signals called impulses
• nerve cells are long, in order to carry electrical signals around the body.
• they also end in branches that connect with muscles, glands or other nerve cells

Question 3

Sperm Cell

Answer 3

• the function of a sperm cell is to carry the male DNA to the female DNA (in an egg cell).
• a long, flexible tail allows the sperm to swim to the egg cell.
• a large number of mitochondria in the middle section provide energy.
• the head carries enzymes.
• these enzymes help the sperm to break through the membrane of the egg cell.

Question 4

Root Hair Cells

Answer 4

• plant root hair cells are adapted to absorb water and mineral ions
• root hair cells take in water and nutrients from the soil
• they are long and thin, which gives them a large surface area
• a large surface area makes it easier to absorb water and nutrients.

Question 5

Xylem Tissue

Answer 5

• xylem tissue transports water up the plant.

- xylem cells are hollow tubes reinforced with lignin for strength.

Question 6

Phloem Tissue

Answer 6

• phloem tissue transports sugar up and down the plant.

- phloem tissue has elongated cells that are adapted to transport food molecules.

Question 7

Organism’s Cell

Answer 7

• all of an organism’s cells contain the same genetic information.
• all of an organism’s cells are the same when it first begins to develop.
• when cells differentiate, they become adapted and specialised for a particular function.

Question 8

Animal Cells and Plant Cells Differentiation

Answer 8

• animal cells differentiate at an early stage of their development.
• cell differentiation continues in mature animals, but this is mainly for replacement and repair only.
• in plants, many types of cell do not lose their ability to differentiate.

Question 9

Stem Cells in Adults

Answer 9

• stem cells in the bone marrow can turn into blood cells and immune cells

Question 10

Stem Cells in medicine

Answer 10

• doctors can take undifferentiated stem cells from a patient.
• the stem cells can then be used to grow new tissue or repair damaged organs.
• for example, stem cell treatment could help paralysed patients or patients with diabetes.

Question 11

Stem Cells Risks

Answer 11

• stem cell treatment has potential medical risks.
• one risk is that viruses can infect stem cells.
• a virus could then be transferred into a patient.
• some people also oppose stem cell research on ethical or religious grounds.

Question 12

Stem Cells in Plants

Answer 12

• cells in the meristem tissue in plant roots and shoots can differentiate into any type of cell.

Question 13

Plant Cloning

Answer 13

• rare plant species can be cloned to protect them from extinction.
• some individual plants display special features such as disease resistance.
• these can be cloned to make lots of disease resistant plants.

Question 14

Eukaryotic Cell

Answer 14

• 5nm to 10 nm
• cell membrane surrounded by cell wall in plants and fungi
• Cytoplasm, cell organelles include mitochondria, chloroplasts in plants and ribosomes
• DNA in a nucleus - plasmids are found in a few simple eukaryotic organisms
• Mitosis

Question 15

Prokaryotic Cell

Answer 15

• most are 0.2 μm – 2.0 μm
• cell membrane - surrounded by cell wall
• cytoplasm, ribosomes, no mitochondria or chloroplasts
• DNA is a single molecule, found free in the cytoplasm - additional DNA is found on one or more rings called plasmids
• Binary fission