B1 6 Variation, Reproduction and New Technology Flashcards

1
Q

Where are genes found?

A

Inside chromosomes made up of DNA, inside the nucleus of gametes.

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2
Q

What are gametes?

A

Sex cells

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3
Q

How many chromosomes do humans have in total?

A

46

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4
Q

What do chromosomes always come in?

A

Pairs

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5
Q

How many pairs of chromosomes do we have in our body?

A

23 pairs

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6
Q

What is a gene’s job?

A

It controls the characteristics of an organism.

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7
Q

How do genes do their job?

A

By controlling all the different enzymes and proteins made in the body.

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8
Q

Why do chromosomes come in pair - what do they represent?

A

One from mother other from father

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9
Q

What do each type gene control?

A

Different characteristics

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10
Q

How do you inherit characteristics from parents?

A

Genes are passed on and carried by gametes.

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11
Q

What are the two types of reproduction?

A

Asexual and sexual

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12
Q

What is asexual reproduction?

A

It only involves one parent and therefore there is no joining of gametes and no genetic variety in the offspring. One cell of 23 pairs of chromosomes split into two sets of 23 pairs to make 46 chromosomes in total. The DNA replicates itself in each cell to form new cells which are genetically identical.

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13
Q

What happens in sexual reproduction?

A

A gamete from each parent (female and male) joins together to form the offspring. Half the chromosomes contribute towards forming the offspring which means there’s genetic variety.

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14
Q

What are the genetically identical offsprings of asexual reproduction known as?

A

Clones

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15
Q

What is meant by the term variation?

A

Differences within a species

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16
Q

What are the two types of variation?

A

Genetic and environmental

17
Q

What is meant by genetic variation? Give an example.

A

When an organism’s characteristics are determined by the genes inherited from their parents.

Eye colour

18
Q

What are genes?

A

The codes inside your cells that control how you’re made.

19
Q

What is meant by environmental variation? Give an example.

A

The environment that organisms live and grow in also causes differences between members of the same species.

Scars caused by accidents

20
Q

Put these statements in order:

  • Inside each cell is a nucleus
  • These chromososmes are made from a helix structure called DNA
  • The DNA contains pairs of genes
  • Your body is made of different cells
  • Inside the nucleus are 23 pairs of chromosomes (46 in total)
  • The genes control what an organism is like
A
  1. Your body is made of different cells
  2. Inside each cell is a nucleus
  3. Inside the nucleus are 23 pairs of chromosomes (46 in total)
  4. These chromososmes are made from a helix structure called DNA
  5. The DNA contains pairs of genes
  6. The genes control what an organism is like
21
Q

Put the following statements into order:

  • Each gamete contains 23 single chromosomes
  • Two gametes fuse together to form a zygote
  • Sperm cells (from the father) and egg cells (from the mother) are called gametes.
  • This means that the growing embryo is different from both its parents.
  • In the zygote the 23 chromosomes join to form 23 pairs of chromosomes (46 in total)
  • The zygote multiplies to form an embryo, it has half its genetic information from the father and half from the mother.
A
  1. Sperm cells (from the father) and egg cells (from the mother) are called gametes.
  2. Each gamete contains 23 single chromosomes
  3. Two gametes fuse together to form a zygote
  4. In the zygote the 23 chromosomes join to form 23 pairs of chromosomes (46 in total)
  5. The zygote multiplies to form an embryo, it has half its genetic information from the father and half from the mother.
  6. This means that the growing embryo is different from both its parents.
22
Q

Tick whether the statement refers to asexual or sexual:

A
23
Q

State an advantage and disadvantage of sexual reproduction?

A

Advantage: faulty material is not always passed on

Disadvantage: it is risky as it relies on two individual sex cells

24
Q

State an advantage and disadvantage of asexual reproduction?

A

Advantage: energy and time used by the organism when looking for a mate is less

Disadvantage: faulty material is definitely passed on

25
Q

How can scientists test variety?

A

Using identical twins brought up by different families.

26
Q

What are the methods involved in cloning through cuttings?

A

First you take a cutting by removing a small piece of the plant. You only need to take part of the stem or just part of a leaf. By using hormone rooting powder then keeping the plant under the right conditions you can create **several **genetically identical plants.

27
Q

State an advantage and disadvantage of using cuttings?

A

Advantage: it’s cheaper

Disadvantage: you can only produce a few plants at the same time

28
Q

What are the methods involved in tissue culture when cloning?

A

We take a few cells from the plant you want to clone, we then place them in a petri dish and stimulate them with plant hormones. We can create thousands of identical plants from just a few cells unlike cuttings.

29
Q

State an advantage and disadvantage of tissue culture?

A

Advantage: you can produce thousands of plants from a few plants rather than several

Disadvantage: it’s very expensive

30
Q

Why would people want clones of plants?

A

As they want plants with new characteristics and uses.

31
Q

Describe how embryos are cloned through embryo transplant?

A
  1. Sperm cells are taken from the male and egg cells are taken from the female with the desired characteristics.
  2. The sperm are then used to artificially fertilise an egg cell
  3. The embryo that develops is then split may times (to form clones) before any cells
  4. These cloned embryos can then be implanted into lots of host females (surrogates)
  5. The babies that are born are genetically identical to each other.
32
Q

State an advantage and disadvantage of embryo transplant.

A
  • *Advantage**: Organisms that are difficult or slow to breed normally can be reproduced quickly.
  • *Disadvantage**: All clones maybe wiped out if a disease comes across
33
Q

Put these statements in order for adult cell cloning:

  • Take an egg from the ovary of a second animal
  • Give the egg a small electric shock to start its dividing
  • The surrogate gives birth to a clone of the first as it has the same DNA
  • Take a small number of cells from an animal (the animal you want to clone)
  • Implant the dividing embryo into the uterus of a surrogate animal
  • Remove the DNA from the nucleus of the egg from the second animal
  • Extract the DNA from the nucleus of the cells extracted from the first animal
  • Insert the DNA from the first animal into the nucleus of the egg taken from the second.
A
  1. Take a small number of cells from an animal (the animal you want to clone)
  2. Take an egg from the ovary of a second animal
  3. Extract the DNA from the nucleus of the cells extracted from the first animal
  4. Remove the DNA from the nucleus of the egg from the second animal
  5. Insert the DNA from the first animal into the nucleus of the egg taken from the second.
  6. Give the egg a small electric shock to start its dividing
  7. Implant the dividing embryo into the uterus of a surrogate animal
  8. The surrogate gives birth to a clone of the first as it has the same DNA
34
Q

State an advantage and disadvantage of adult cell cloning.

A

Advantage: can produce medically useful animals

Disadvantage: reduces variety so more likely to get wiped out

35
Q

What are the methods involved in genetic engineering?

A

(use image for method)

36
Q

What are the advantages and disadvantages of genetic engineering?

A

Advantages: can improve growth rates of animals and plants

can improve food value of crops as genetically modified crops

can be engineered to produce plants to make own pesticide or be resistant to herbicide used to kill weeds

Disadvantages: insects may become herbicide resistant

farmers in poor countries need to buy seeds every year