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A Level Biology > Chapter 3: Cell division > Flashcards

Chapter 3: Cell division Flashcards

1
Q

Phases of the cell cycle?

A

Interphase which includes G1, S, G2, phases

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2
Q

What happens in G1 phase?

A

Cell increases in size, organelles like mitochondria and cytoplasm replicate

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3
Q

What happens in the S phase?

A

Synthesis phase, the DNA is replicated in the nucleus

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4
Q

What happens in the G2 phase?

A

Cell continues to grow in size, checks chromosomes for DNA replication errors, repairs them

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5
Q

Why do cells go to the G0 phase?

A

They’ve been differentiated and can no longer divide, damaged DNA or there are too many cells in the body

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6
Q

What does the G1 and G2 checkpoint do?

A

Checks if cell is big enough and has been replicated correctly without any errors

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7
Q

Explain the spindle-assembly checkpoint?

A

Also known as metaphase. Chromosomes are attached to spindles and get aligned along the equator of the cell. Necessary to pass or mitosis can’t happen

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8
Q

Order of mitosis stages?

A

Prophase, Metaphase, Anaphase and Telophase

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9
Q

Prophase in mitosis?

A

Chromosomes condense and thicken, this makes them visible. Nuclear envelope starts to break down. Spindle fibres start to form

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10
Q

Metaphase in mitosis?

A

Spindle fibres move chromosomes into the centre of the cell called the metaphase plate

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11
Q

Anaphase in mitosis?

A

Centromeres holding the chromatids together separate to either poles by the spindle fibres

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12
Q

Telophase in mitosis?

A

Chromatids now called chromosomes and assemble at poles. Nuclear envelope starts to form around them. then its cytokinesis.

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13
Q

Where does chiasmata take place and what is it?

A

Anaphase 1, it is the break and rejoining of chromatids due to them crossing over, cause DNA change and genetic variation

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14
Q

What is crossing over?

A

Takes place in Prophase 1 and it is the chromatids entangling because they were brought to close together

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15
Q

Where does independent assortment take place and what is it?

A

Metaphase 1, its chromosomes facing different directions and different poles, cause genetic variation

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16
Q

What happens in Telophase 2?

A

The chromosomes uncoil and form chromatids again

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17
Q

what is the level of organisation?

A

Specialised cells, tissue, organs, organ systems, organisms

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18
Q

How are erythrocytes specialised?

A

Red blood cells, flattened biconcave shape which increases SA:V. No nuclei which means more space for haemoglobin to carry oxygen. Flexible to fit through capillaries

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19
Q

How are neutrophils specialised?

A

White blood cells essential role in immune system. Multi-lobed nucleus easier to fit through small gaps to reach infections. Granular cytoplasm contains a lot of lysosomes to attack and break down pathogens

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20
Q

How are sperm cells specialised?

A

Deliver genetic information to female gamete. Have a flagellum = capable of movement. Lots of mitochondria = energy needed to swim. Head of sperm (acrosome) contains digestive enzymes to digest protective layers of the ovum so sperm can penetrate and fertilise egg

21
Q

How are palisade cells specialised?

A

Contain A LOT of chloroplasts = absorbs more light via photosynthesis. Closely packed to form continuous layer. Thin cell walls = increases rate of diffusion. Large vacuole to maintain turgor pressure

22
Q

Root hair cells, how are they specialised?

A

Present at surfaces of roots near growing tips. Have long extensions (root hairs) which increase SA:V ratio. This maximises the uptake of water and minerals from the soil

23
Q

How are guard cells specialised?

A

On the surface of leaves. Form small openings called stomata which allow CO2 to enter plant for photosynthesis. When guard cells loose water = less swollen and change shape to prevent more water loss.

24
Q

What is cartilage?

A

Connective tissue. Found at ends and between bones. Flexible and prevents bones from rubbing together and damaging themselves

25
Q

Name the 4 types tissue in mammals?

A

Nervous tissue, Epithelial tissue, Muscle tissue and Connective tissue

26
Q

How is xylem tissue specialised?

A

Responsible for transport of water and minerals throughout plants. Composed of elongated dead cells. Walls strengthened with lignin. Has rings for structural support too.

27
Q

3 types of muscle tissue?

A

Smooth, skeletal and cardiac

28
Q

2 different types of epithelium

A

Ciliated and Squamous

29
Q

How is ciliated epithelium adapted for its function?

A

Has cilia (hair-like projections) on surface to sweep mucus away from lungs. Goblet cells present to trap unwanted particles

30
Q

How is squamous epithelium adapted for its function?

A

Very thin which allows it to have rapid diffusion across surfaces.

31
Q

How is the phloem specialised?

A

Transports nutrients around plants. Has sieve tubes within it and companion cells for energy to diffuse in

32
Q

The name for undifferentiated cells?

A

Stem cells

33
Q

How many times can stem cells divide?

A

As much as they want. Once specialised they loose ability to divide

34
Q

What does potency mean?

A

A stem cells ability to differentiate into different cell types. Greater the number the more potent it is

35
Q

Explain totipotent?

A

Stem cells that can differentiate into any cell type

36
Q

Explain pluripotent?

A

Stem cells that can form all tissue types but not whole organisms. Present in early embryos

37
Q

Explain multipotent?

A

Stem cells that can only form a range of cells within a certain type of tissue

38
Q

What phase does a cell spend most of the time in?

A

Interphase

39
Q

Which stage of mitosis is the longest?

A

Metaphase

40
Q

Causes for genetic variation?

A

Mutation, Independent assortment, chiasmata, changes combination of alleles

41
Q

Cytokinesis?

A

Cytoplasm dividing

42
Q

What is the cytoplasm made of?

A

Cytosol

43
Q

How many cell divisions for mitosis and meiosis?

A

Mitosis = 1 cell division and Meiosis = 2 cell divisions

44
Q

What type of reproduction for both divisions?

A

Mitosis is asexual and meiosis is sexual

45
Q

How is the upper epidermis specialised?

A

Transparent to allow light through onto palisade layer, covered by a waxy cuticle to be waterproof and reduce water loss

46
Q

Diploid meaning?

A

Cells with two complete sets of chromosomes

47
Q

Haploid meaning?

A

Cells with only one complete set of chromosomes

48
Q
A

A Level Biology (9 decks)

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