growth and development Flashcards

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1
Q

what is meiosis?

A

cell division used to produced gametes

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2
Q

what is mitosis?

A

division of body cells to produce new cells

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3
Q

what is phototropism?

A

plants response to the direction of light by changing direction in which they grow in order to survive

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4
Q

explain chromosomes?

3 answers

A
  • made from DNA molecules
  • found in nucleus
  • can be grouped in pairs
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5
Q

what are the 4 bases?

A

strands of DNA are made up of units linked by bases

A pairs with T
C pairs with G

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6
Q

what does the order of the bases make up?

A

genetic code which gives instructions for assembly of a protein

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7
Q

what is the DNA molecule?

A
  • a double helix

- 2 strands facing each other

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8
Q

where does protein synthesis occur?

A

cytoplasm

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9
Q

how is genetic code carried to the cytoplasm?

A

genes dont leave nucleus so mRNA is produced in nucleus, using DNA as the template

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10
Q

how are proteins assembled?

A

on organelles in the cytoplasm called ribosomes

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11
Q

what does therapeutic cloning involve?

A
  • replacing nucleus of an egg by nucleus of a body cell

- stimulating egg cell to divide to produce embryo

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12
Q

what are adult stem cells?

A

differentiate into limited number of cell types eg bone marrow cells into diff types of blood cell

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13
Q

what are stem cells used for?

A

produce new cells to replace damaged cells

help treat disorders

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14
Q

what happens in specialised cells?

A

only genes needed to enable cell to function as that type of cell is switched on

in embryonic, any gene can be switched on

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15
Q

what are the main processes of the cell cycle?

A
  • cell growth

- mitosis

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16
Q

what happens at fertilisation?

A

games join to form a zygote with 46 chromosomes

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17
Q

how are plants reproduced?

A

1) cuttings taken
2) cuttings put in a rooting hormone
3) roots form and new plants develop
4) new plants genetically identical to parent plant

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18
Q

what are xylem tubes used by the plant to do?

A
  • transport water and soluble mineral salts from roots to stem and leaves
  • replace h2o lost during transpiration + photosynthesis
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19
Q

what are phloem tubes used by the plant to do?

A
  • transport dissolved food to whole plant for respiration or storage
20
Q

what are the 2 types of meristem?

A
  • lateral:
    increased girth
  • apical:
    increased height + longer roots
21
Q

what is the advantage of using adult cells?

A

for growing replacement tissue so can be taken from patient, so patients immune system not will reject transplant

22
Q

what are embryonic stem cells?

A

completely unspecialised, can be used to form any cell type

23
Q

what happens when a light source is directly overhead?

A
  • auxin evenly spread through shoot

- shoot grows straight up

24
Q

what happens when a light source is at an angle?

A
  • auxin destroyed near light source
  • auxin concentrated on side furthest away from light
  • shoot bends towards light
25
Q

what happens when the tip of the shoot is removed or covered in opaque material?

A
  • plant will continue to grow upwards
26
Q

what happens when the tip is covered with a transparent cap?

A
  • still grow towards light source
27
Q

how does phototropism work?

A
  • auxin produced at tip, moves down shoot causing cells to grow
  • when light shines on shoot, auxin near light source destroyed so more auxin on far side away from light causing cells to lengthen faster so shoot bends towards light.
28
Q

auxins are the main plant hormones used in horticulture which what?

A
  • affect cell division

- cause cells to grow in size under tip so stem/roots grow longer

29
Q

up to the 8 cell stage, all cells in a human embryo are what?

A
  • unspecialised

- can have any gene switched on to form any king of specialised cell

30
Q

after 8 cell stage, cells in an embryo are what?

A
  • become specialised

- form diff types of tissue

31
Q

why are some genes switched off?

A

cell only produces protein it needs to carry out its role.

in specialised cells, only genes needed for cell to function are switched on as its only requires specific proteins

32
Q

what is an example of adult stem cells producing cells of a certain type?

A

cells for creating blood cells in bone marrow encouraged to grow more of that type of cell by switching on inactive genes in nuclei

33
Q

where can replacement tissue be grown?

A

lab, sometimes host animal eg mouse used to maintain a blood supply during growth

34
Q

how do plant cells divide?

A

mitosis

new cells in plants specialise into cells of:

  • roots
  • leaves
  • flowers

plants grow in height and width unlike animals

35
Q

where do plant growth occur?

A

areas called meristems which are sites where unspecialised cells are dividing by mitosis, cells then differentiate and become specialised

36
Q

if the hormonal conditions in their environment has changed, the unspecialised plant cells can develop into other what?

A
  • tissues:
    xylem, phloem
  • organs
    flowers, roots, leaves
37
Q

some plant cells remain unspecialised, what does this allow them to do

A

develop into any type of plant cell, allow clones of plants with desirable features to be produced by cuttings

38
Q

what happens during fertilisation?

A

male + female gamete fuse together to produce zygotr

39
Q

mitosis occurs for what?

A
  • growth
  • replace old tissue
  • repair
40
Q

mitosis - when a cell enters the growth phase of the cycle, what happens?

A
  • number of organelles increase

- chromosomes are copied

41
Q

mitosis - when a cell enters division phase of the cycle, what happens?

A
  • copies of chromosomes separate

- cell divides

42
Q

each new cell in mitosis has what?

A
  • same genes as parent
  • identical set of chromosomes as parent
  • same number of chromosomes as parent
43
Q

what do genes control?

A
  • growth and development

- development of characteristics eg eye colour

44
Q

meiosis and sexual reproduction produce variation between offspring and parents how?

A
  • when games fuse, info combined
  • each offspring has diff combination of alleles
  • offspring has diff characteristics
45
Q

what do sequences of bases in a gene determine?

A

order which amino acids join together to make protein

46
Q

whats a triplet code?

A

group of 3 base pairs codes for 1 amino acid in a protein chain

20 diff amino acids can be made

47
Q

what is the process of amino acids making protein?

A

1) DNA unravels at correct gene
2) copy of coding strand made to produce mRNA
3) mRNA copy moves from nucleus into cytoplasm
4) triplet code decoded by ribosomes
5) amino acids joined together to form polypeptide