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Question 1

Name 6 specialised cells? Which are in humans and which are in animals?

Answer 1

Muscle cell, Sperm cell and Nerve cell in animals

Root hair cell, phloem and Xylem in plants

Question 2

What is a stem cell?

Answer 2

An undifferentiated cell which has the capacity to become any type of cell.

Question 3

Name the places you can find stem cells in a human

Answer 3

Bone marrow and embryonic cells

Question 4

What is Therapeutic cloning?

Answer 4

using adult cells to produce a cloned embryo of an adult to provide perfectly matched embryonic stem cells

Question 5

What’s the function of sperm cell and how is it specialised for this function?

Answer 5

• reproduction (get the make DNA to the female DNA)
• long tail and a streamlined tail to swim to the egg
• many mitochondria to provide energy
• enzymes to digest through the egg membrane

Question 5

What’s the function of a nerve cell and how is it specialised for this function?

Answer 5

• rapid signalling (carry electrical signals from different parts of the body)
• the cells are long to cover more distance
• branches connections at the ends to connect to other nerve cells
• form a network

Question 5

What’s the function of a muscle cell and how is it specialised for this function?

Answer 5

• contractions
• they’re long (so have space to contract)
• contain lots of mitochondria to generate energy for contraction

Question 6

What’s the function of a root hair cell and how is it specialised for this function?

Answer 6

• specialised for absorbing water and minerals
• has long ‘hair’ that stick out into the soil which gives the plant a big surface area
• for absorbing water and minerals ions

Question 7

What’s the functions of Phloem and Xylem and how are they specialised for their functions?

Answer 7

• phloem and Xylem cells form phloem and Xylem tubes, which transport substances (food and water) around the plants
• Xylem are hollow
• phloem have a few sub-cellular structures
• so stuff can flow through them they both form tubes.

Question 8

What’s differentiation?

Answer 8

• the process by which a cell changes to become specialised for its job
• when they change they develop different sub cellular structures and turn into different types of cells, and carry out specific functions

Question 9

When does most differentiation occur in an organisms?

Answer 9

• most animals cells differentiate at an early cell
• (when they differentiate in mature animals it’s for repairing and replacing cells like skin or blood cells)
• plants mostly retain the ability to differentiate through there life times

Question 10

How do prokaryotic cells (bacteria) replicate?

Answer 10

• binary fission, where one cell splits in half into 2
• the plasmids replicate and move to opposite ends of the cell, the cytoplasm divides and a new wall is formed
• 2 daughter cells are produced
• (in the right conditions sone bacteria can replicate in 20 minutes)

Question 11

What are 2 conditions which are optimal for binary fission?

Answer 11

A warm environment and lots of nutrients

Question 12

What’s a culture medium?

Answer 12

It’s where bacteria are grown in contains: minerals, proteins, vitamins, etc.
-it can be a nutrient solution or Colonies on an ager gel plate

Question 13

In school labs what temperature are cultures if microorganisms kept at?

Answer 13

• not above 25 C

- because more harmful pathogens are more likely to grow above this temperature

Question 14

How must you prepare an uncontaminated culture?

Answer 14

• petri dishes & culture mediums: must be sterilised by heating at a high temperature to kill unwanted microorganisms on them
• inoculating loops: used to transfer microorganisms to the culture must be sterilised by passing them through a flame
• the lid of the Petri dish should be tightly taped on (after transferring the bacteria) to stop microorganisms for the air getting in
• the Petri dish should be stored upside down to stop condensation falling onto the agar surface
• incubated at 25 C

Question 15

What do chromosomes do?

Where are they found?

Answer 15

• found in the nucleus, your genetic material is in form of chromosomes
• there’s 2 copies of every chromosome (One has been inherited from the mother, the other from the father)
• Humans have 23 pairs of chromosomes (there found in pairs), so 46 in total
• each chromosome has different genes so control the development of different characteristics

Question 16

What’s the name of the complete set of chromosomes for a species?

Answer 16

karyotype

Question 17

Why would mitosis happen?

Answer 17

1. Growth, to make the organism bigger
2. Repair of damaged tissues or replacement of worn-out cells
3. Asexual reproduction

Question 18

What’s the cell cycle?

Answer 18

• the time between the formation of a cell and when it undergoes cell division
• the division is mitosis because the new cells formed must contain all of the genetic information of the previous cells

Question 19

What are 2 stages of the cell cycle?

Answer 19

1. Growth and DNA replication

2. mitosis

Question 20

Explain the full cell cycle

Answer 20

• the cell grows then increases the number of sub-cellular structures (ribosomes, mitochondria)
• The DNA replicate and forms 2 copies of each chromosome. And forms X-shaped chromosomes
• in mitosis the chromosomes line up in the centre of the cell and cell fibres pull them apart. 2 arms of each chromosome go to opposite sides
• membranes form around each set of chromosomes, the nuclei
• then the cytoplasm and cell membrane divide

Question 21

What’s produced in mitosis?

Answer 21

• 2 new daughter cells

- they contain the sane genetic information there DNA is also identical to the parent cell