Stem Cells

Question 1

What is the definition of a stem cell

Answer 1

An renewing source of undifferentiated cells which have te potential to differentiate and become specialised cells

Question 2

What is the definition of differentiation?

Answer 2

The process by which stem cells become specialised cell

Question 3

What is a Totipotent stem cell?

Answer 3

• An undifferentiated cell that has the capacity to self-renew by dividing
• They can develop in to any type of cell including extra-embryonic stem cells like placenta or umbilical chord

Question 4

What is a pluripotent stem cell?

Answer 4

• An undifferentiated which has the capacity to self-renew by dividing
• They can develop into all types of adult cell

Question 5

What is a multipotent stem cell?

Answer 5

• An undifferentiated cell with the capacity to self-renew by dividing
• They can develop into all types of cell which are present in a specific tissue or organ

Question 6

Which type of stem cell is found in the blastocyst?

Answer 6

Pluripotent stem cells

Question 7

Which type of stem cells are embryonic stem cells?

Answer 7

Pluripotent stem cells

Question 8

Which type of stem cell are in bone marrow?

Answer 8

Multipotent stem cells

Question 9

Explain how the erythrocytes are produced from the stem cells in bone marrow

Answer 9

• The multipotent stem cells divide by mitosis
• They dfferentiate and specialise to form erythrocytes by producing a lot of haemoglobin protein in order for oxygen to be carried in the blood
• The stem cells will also remove the nucleus to allow for more space for the oxygen-carrying haemoglobin

Question 10

Explain how neutrophils are produced from the stem cells in bone marrow

Answer 10

• The multipotent stem cells divide by mitosis and differentiate to form neutrophils by changing the shape of the nucleus to form a multilobed nucleus.
• They need to produce many lysosomes which contain enzymes which attack pathogens

Question 11

Explain how xylem vessels are formed meristem cells in the vascular cambium

Answer 11

• Xylem vessels are formed from merristem cells in the cambium.
• The vessels are reinfrced with lignin which eater-proofs them and strengthens them against negative pressure

Question 12

Explain how phloem vessels are formed meristem cells in the vascular cambium

Answer 12

The meristem cells produce parynchyma cells which form the companion cells and siee-tube elements/ The sieve tube elements contain perforated end-walls called sieve-plates which allow assimilates to be transported up and down the phloem

Question 13

Give three potential uses of stem cells in research and medicine

Answer 13

1. Repair of damaged tissues
2. Treatment of neurological conditions like Alzheimer’s and Parkinsons disease
3. Research into developmental biology