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HSC BIOLOGY > BP S2 > Flashcards

BP S2 Flashcards

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1
Q

Mendel proposed a…

A

Particulate hypothesis of inheritance, this means that the discrete units are inherited from each parent and explained why some features seemed to jump generations and reappear in a later generation.

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2
Q

Gregor Mendel?

A

(1822-1844) an Augustinian monk who is known as the father of genetics. His work demonstrated that inheritance occurred in a definite patterns, marking the beginning of modern genetics.

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3
Q

Mendel used the?

A

Garden pea.

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4
Q

With the garden pea, Mendel established…

A

Seven easily distinguishable characteristics, or traits that had alternate forms which Mendel thought were controlled by factors (genes).

Mendel bred the plants for two years to make sure that the plants used in his experiments were all true breeding (homozygous.)

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5
Q

Name the seven traits studied by Mendel.

A

Seed shape, flower colour, seed colour, pod shape, pod colour, stem height, flower position.

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6
Q

Name alternate forms for seed shape

A

Round/wrinkled

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7
Q

Name alternate forms for flower colour

A

Purple/white

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8
Q

Name alternate forms for seed colour

A

Yellow/green

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9
Q

Name alternate forms for pod shape

A

Inflated/constricted

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10
Q

Name alternate forms for pod colour

A

Green/yellow

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11
Q

Name alternate forms for stem height

A

Tall/short

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12
Q

Name alternate forms for flower position

A

Terminal (at end of stem) / Axillary (in the leaf axil)

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13
Q

Mendel crossed pure breeding plants with?

A

Alternate forms of each trait, eg he crossed short plants with tall plants. (cross pollination)

He made sure they did not self pollinate by removing all immature stamens.

This type of genetic cross, in which only one characteristic is studied is known as monohybrid cross.

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14
Q

At the time Mendel was experimenting it was thought that…

A

The characteristics of offspring were blended results of the parents characteristics. E.g. a tall plant with a short plant would make a medium size plant.

Medel proved this wrong by crossing a tall plant with a short plant, all the plants in this generation (F1) were tall, and it appeared the shortness had disappeared.

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15
Q

Mendel suggested that for each trait…

A

One factor was dominant and one was recessive.

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16
Q

When Mendel continud experimenting after the F1 generation what did he do?

A

He Allowed the F1 generation to self pollinate and cross pollinate with each other. Which then lead to the F2 generation that contained both short and tall plants. Short had in fact not disappeared it had become recessive. The F2 generation included the ratio 3:1 tall:short. Mendel then found te same result for the rest of the characteristics he studied.

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17
Q

What did Mendel conclude from his experiments?

A
  • Characteristics were not blended but were discrete units
  • Each characteristic was controlled by a pair of factors
  • The factors separated from one another when the sex cells were formed (Mendels law of Segregation)
  • At fertilisation the offspring received one factor from each parent randomly (Mendels law of independent assortment)
  • One factor was dominant while the other was recessive.
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18
Q

Today we call Mendel’s factors….

A

Genes, and the alternate forms known as alleles.

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19
Q

Why was Mendel’s experiments successful and reliable?

A
  • Kept accurate records
  • Looked at individual characteristics (traits) that were easy to distinguish and not the whole plant
  • Controlled the pollination process carefully
  • Chose peas, which were easy to grow and produced offspring rapidly and normally self pollinated.
  • Analysed his results mathematically
  • Used large numbers of plants and repeated his experiments many times.
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20
Q

Why was Mendel fortunate?

A

That all the seven factors that he studied were all on different chromosomes and were not genetically linked.

21
Q

How many years did Mendel breed for?

A

Several years

22
Q

When did Mendel publish his results?

A

1866

23
Q

Name the dominant features in all seven traits of Mendel’s experiments.

A
  • Round seed
  • Yellow seed
  • Mooth pod
  • Green pod
  • Purple flower
  • Tall stem
  • Terminal flowers
24
Q

Name the recessive features in all seven traits of Mendel’s experiments.

A
  • Wrinkled seed
  • Green seed
  • Constricted pod
  • Yellow pod
  • White flower
  • Short stem
  • Axial flowers
25
Q

Mendel repeated his experiments with a large number of crosses… these gave his results?

A
  • Statistical verification.
26
Q

Mendel worked out the law of….

A

Segregation, which states that for each characteristic there are two factors which segregate, with one factor in each reproductive cell, and then recombine at fertilisation. The characteristics do not blend one dominates the other.

27
Q

Why wasn’t Mendel’s work recognised?

A

Because his work was presented to a small group of scientists and posted into a small journal. Since he was also an Augustinian monk and did not move in scientific circles the significance of his work was not recognised at that time.

28
Q

Define heterozygous?

A

Describes the situation in which each member of a pair of alleles is different from the other. If one is dominant, it may be expressed or if they are co dominant it’ll both be expressed.

29
Q

Define dominant and recessive alleles?

A

Are forms of a gene that interact in such a way that one is expressed (dominant) and the other is not expressed (recessive) if the occur together. E.g. Tt = tall.

30
Q

Define genotypes?

A

Are the genetic makeup for a certain characteristic, usually occurring as a pair of alleles AA Aa aa

31
Q

Define Phenotype?

A

Is the observable characteristics that result from the interplay of alleles and environment: what an organism looks like.

32
Q

Define Allele?

A

Are different forms of the same gene (A, B and O blood type)

33
Q

Define Gene?

A

Are discrete segments of the long molecules of DNA that are found on chromosomes and code for a polypeptide.

34
Q

How to do a punnet square?

A

Get the parent genotypes. And times them by eachother

Tt x Tt
turn into gametes.
T & t x T & tthen place on opposite sides of a table
Then write the phenotypes of the offspring.
Tall:Dwarf
3:1
75%:25%

35
Q

In pedigrees what is the symbol of the clear square?

A

Unaffected male

36
Q

In pedigrees what is the symbol of the clear circle?

A

Unaffected female

37
Q

In pedigrees what is the meaning of the symbol coloured in?

A

The person is affected.

38
Q

What is the aim of hybridisation?

A

To create new and better combinations of characters.

39
Q

Mendel’s model provided scientists with an understanding that could be used to improve agricultural crops. How so?

A

Plant breeders recognised that characters could be without being changed, be brought into new combinations in hybrid organisms.

They’d carry out systematic crosses between different varieties of one species to form hybrids. That had new combinations of desirable characters.

40
Q

What are the two types of hybridization?

A
  1. The crossing of different varieties of one species to produce new varieties with different combinations of characteristics.
  2. Involves the crossing of different but closely related species.
41
Q

In general hybrid plants are more?

A

Are more vigorous and higher yielding compared with their true breeding parents.

42
Q

Describe the outcomes of hybridisation.

A

The outcome is not always an improvement, it is important to note that when hybrid offspring are produced artificially they are designed to be cultivated or reared under controlled conditions of intensive agriculture, horticulture or farming and may not be suited to conditions in the wild.

43
Q

Discuss why wheat hybridisation in Australia was necessary.

A

In the late 1800s flower produced in Australia was too poor to be used for baking bread for human consumption. Flour had to be imported principally from Canada. The first wheats to be grown in Australia were old English varieties that ripened too late to survive the hot summer. It produced poor flour, and was affected by many fungal diseases.

44
Q

Discuss the loop hole to better wheat in Australia due to hybridisation.

A

William Farrer pioneered Australian wheat research, systematically used cross breeding (hybridisation) to improve bread wheat. Farrer crossed mainly bread wheat along with one other (triticum aestivum), also with a pasta wheat.

Farrer succeeded in breeding many new wheat varieties that were more suitable for the Australian climate and environment.

45
Q

Characteristics of Farrer wheat for Australia

A
  • Earlier ripening to suit shorter growing season in Australian wheat growing areas, early ripening was recessive to late ripening.
  • Improved baking quality
  • Improved yield (grains per head)
  • Resistance to fungal disease “bunt”
46
Q

What was the end product for Farrer?

A

A wheat called federation that took many years to engineer that went out for commercial use in 1901.

47
Q

monohybrid crosses involve looking at…

A

one characteristic only

48
Q

What is learnt with Mendels monohybrid crosses involving simple dominance in relation to the F1 generation and the F2 generation?

A

When looking at the results of the F1 generation (homozygous partners) it is seen that only the dominant genes in the experiments was exhibited, though in the F2 generation (heterozygous partners) there was a ration of 3:1 with one being the recessive gene.

HSC BIOLOGY (21 decks)

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