B2 - Cell Structure and Transport Flashcards

Exam revision - Aiming for grade 7 or above.

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1
Q

B2.1 - Aiming for 4 - How many chromosomes are found in the nucleus of human body cells?

A

46

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2
Q

B2.1 - Aiming for 4 - How many chromosomes are found in the nucleus of gametes?

A

23

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3
Q

B2.1 - Aiming for 4- What is the meaning of the keywords, mitosis, chromosomes, gene, gametes.

A
  1. Mitosis - process of nuclear division in body cells.
  2. chromosomes - coiled structures made up of DNA.
  3. gene - short sections of DNA that code for proteins.
  4. Gametes - A gamete is a sex cell. In humans, gametes are sperm and eggs
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4
Q

B2.1 - Aiming for 6 - Explain why chromosomes are normally found in pairs.

A

One chromosome is inherited from the mother and one is inherited from the father. The chromosomes in each pair carry the same gene in the same location.

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5
Q

B2.1 - Aiming for 6 - Describe situations where mitosis is occuring.

A

Whenever more cells are needed. happens throughout the entire lifespan of a living organism (human, animal or plant) but most rapidly during periods of growth.

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6
Q

B2.1 - Aiming for 6 - Describe the process of mitosis using the keywords.

A

Chromosomes contain genes of male and female parent. Those chromosomes multiply from 2 genes to 4 genes and then divide.

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7
Q

B2.1 - Aiming for 8 - Explain why genetic material must be doubled during mitosis.

A

the cells separate the duplicated chromosomes into the two daughter cells. In this way the correct inheritance of genetic information from one generation of cells to the next is assured.

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8
Q

B2.1 - Aiming for 8 - Explain in detail what happens at each stage of the cell cycle.

A

1st: cells grow and increase in mass, replicate DNA and synthesise more organelles. Ribosomes, Mitochondria and sub-cellular structures are produced.
2nd: Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.
3rd: Cytoplasm and cell membrane divide - two identical daughter cells are produced.

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9
Q

B2.1 - Aiming for 8 - Write a detailed explanation on why mitosis is an important process in living things and how characteristics are inherited.

A

Chromosomes carry genetic information in DNA. Mitosis ensures that when a cell divides, each new cell produced has the same genetic information.

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10
Q

B2.2 - Aiming for 4 - Define the terms growth and differentiation

A

Differentiation - The process where a cell becomes specialised to its function.
Growth - an increase in size and mass of a particular organism over a period of time.

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11
Q

B2.2 - Aiming for 4 - State why plant clones are genetically identical to each other.

A

Plants are cloned to produce identical plants quickly and economically. Clones are genetically identical to the original plant providing the meristem cells

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12
Q

B2.2 - Aiming for 6 - Describe the importance of cell differentiation in multicellular organisms

A

Differentiated cells are important in a multicellular organism because they are able to perform a specialised function in the body. Multicellular organisms must retain some unspecialised cells that can replenish cells when needed.

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13
Q

B2.2 - Aiming for 6 - Explain how tissue culture creates a clone of a plant

A

Scientists take a plant they want to clone, divide the plant into tiny pieces. The plant hormones stimulate the plants to grow and develop into fully-grown clones.

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14
Q

B2.2 - Aiming for 8 - Compare and contrast differentiation in plants and animals

A

In animals the cells differentiate early on and lose the ability to specialise
Only stem cells can specialise
In plant cells – mitosis takes place in the meristems which are found in the shoots and root tops
Plants can differentiate all the way throughout their life
Plants can also CLONE themselves (make identical copies) using asexual reproduction

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15
Q

B2.2 - Aiming for 8 - Explain why it is easier to clone a plant compared to an animal

A

A plant cell can become any cell the plant needs to survive similar to a stem cell. Cloning animals is a much more complicated process and often comes with birth defects

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16
Q

B2.3 - Aiming for 4 - What is a stem cell?

A

A stem cell is a cell that is not differentiated

17
Q

B2.3 - Aiming for 4 - What can plant stem cells be used to create?

A

Plant stem cells can be used to create clones.

18
Q

B2.3 - Aiming for 6 - Describe the differences between embryonic and adult stem cells.

A

Embryonic stem cells are totipotent and can become any type of cell and found in the embryo whereas adult stem cells are multipotent, but can only become specific cells (blood, bone) and are found in bone marrow.

19
Q

B2.3 - Aiming for 6 - Why are plant clones produced in the agriculture industry?

A

Plants are cloned to produce identical plants quickly and economically.

20
Q

B2.3 - Aiming for 8 - Explain why embryonic stem cells are more useful for helping medical conditions

A

Embryonic stem cells are pluripotent, meaning they can divide into more stem cells or can become any type of cell in the body. This can be used to regenerate or repair dead tissue and organs.

21
Q

What is differentiation?

A

Cells are initially unspecialized, they can become different types of cells and during differentiation, certain genes are switched on or off to become a specialized cell.

22
Q

What are the adult stem cells?

A

stem cells found in adults that can differentiate and form a limited number of cells

23
Q

What is the cell cycle?

A

three-stage process of cell division in a body cell that involves mitosis and results in formation of two daughter cells.

24
Q

What is cloning?

A

production of identical offspring by asexual reproduction

25
Q

What does differentiate mean?

A

process where cells become specialised for a particular function

26
Q

What are embryonic stem cells?

A

stem cells from an early embryo that can differentiate to form the specialised cells of the body.

27
Q

what is mitosis?

A

part of the cell cycle where one set of new chromosomes is pulled to each end of the cell forming two identical nuclei during cell division

28
Q

What are stem cells?

A

undifferentiated cells with potential to form a wide variety of different cell types.

29
Q

What is therapeutic cloning?

A

process where an embryo is produced that is genetically identical to the patient so the cells can be used in medical treatment.

30
Q

what is a zygote?

A

the single new cell formed by the fusion of gametes in sexual reproduction.

31
Q

What are the advantages and disadvantages of using stem cells from embryos instead of adults (6 marks)

A
Embryo:
Pros: 
•can treat a wide range of diseases
(pluripotent – can become all of the cells)
•Painless procedure 
•better to use cells rather than waste them.
Cons:
•harm/death to embryo
•long-term effects unknown
•embryo cannot give consent.
Adult:
pros:
•reliable technique
•no ethical issues or adult can give permission
•quick recovery
•does not kill donor.
Cons:
•involves an operation
•people may not want to be donors as it is painful
•few cell types can be formed or fewer diseases can be treated.(multipotent)
32
Q

B2.4 - Aiming for 4 - List some arguments for and against the use of stem cells.

A

For:
Able to turn into different types of cells.
Can cure a wide range of diseases.

Against:
Adult stem cells could be infected with a virus.
Huge financial investment into stem cells.

33
Q

B2.4 - Aiming for 6 - Explain the reasons for ethical and religious objections against stem cells.

A

Religious beliefs mean some cannot accept interference of process of human reproduction. They believe it is wrong as stem cells are living cells, and that it’s a violation of human rights.

34
Q

B2.4 - Aiming for 8 - Explain the process of therapeutic cloning organisms.

A

Therapeutic cloning involves removing the nucleus of an egg cell, replacing it with the material from the nucleus of a “somatic cell” (such as a skin cell), and stimulating this cell to begin dividing.

35
Q

B2.4 - Aiming for 8 - Evaluate the use of stem cells.

A

Stem cells can divide to produce new cells, which can divide into different cell types. They have the potential to be transplanted into patients to treat medical conditions and diseases. They could be used to replace cells that have been damaged or destroyed, for example: in type 1 diabetes.