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sem 2 science > biology > Flashcards

biology Flashcards

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Biology 101 flashcards
1
Q

What does DNA stand for?

A

Deoxyribonucleic acid

DNA stands for Deoxyribonucleic acid.

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2
Q

Where is DNA found in the body?

A

In the nucleus of every cell in the body except red blood cells

DNA is found in the nucleus of every cell in the body except red blood cells.

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3
Q

What does DNA carry?

A

Building instructions for proteins

DNA carries the building instructions for proteins.

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4
Q

What does DNA have the same structure as?

A

Same in every living thing on Earth

DNA has the same structure in every living thing on Earth.

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5
Q

What is DNA made up of?

A

Repetitive nucleotides

DNA is made up of lots of repetitive nucleotides.

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6
Q

What is a nucleotide made up of?

A

Phosphate group, deoxyribose sugar, one of four nitrogenous bases

One nucleotide is made up of a phosphate group, a deoxyribose sugar, and one of four nitrogenous bases.

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7
Q

What are the four nitrogenous bases in DNA?

A

Adenine, thymine, guanine, cytosine

The nitrogenous bases in DNA are labelled A, T, G, and C, which stand for adenine, thymine, guanine, and cytosine.

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8
Q

What is the complementary base pairing rule in DNA?

A

A always bonds with T, C always bonds with G

In DNA, A always bonds with T and C always bonds with G - this is called the complementary base pairing rule.

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9
Q

What does DNA look and described as

A

A twisted rope ladder; this is called the double helix.

Think of DNA as a twisted rope ladder; this is called the double helix.

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10
Q

What are chromosomes?

A

thread like structure made of DNA and proteins
found in the nucleus of a cell
## Footnote

When the cell is about to divide though it all collects together and compresses into structures called chromosomes.

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11
Q

How many chromosomes do humans have?

A

46: 23 from each parent, 23 pairs.

Humans have 46 chromosomes: 23 from each parent, so 23 pairs.

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12
Q

What determines biological gender?

A

The presence or absence of the Y chromosome.

The presence or absence of the Y chromosome determines your biological gender.

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13
Q

of the 23 pairs of chromosomes, what is 1 pair called

A

sex chromosomes

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14
Q

What is a gene and what is it made of?

A

the basic unit of heredity passed from parent to child, made up of DNA
## Footnote

A gene is a sequence of bases that carry the building instructions for a single

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15
Q

Are the sequences of bases for each gene the same?

A

No, the sequence of bases for each gene is different.

This diversity in gene sequences is what gives rise to the variety of proteins in living organisms.

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16
Q

Can the number of bases in a gene vary?

A

Yes, the number of bases in a gene can also vary.

This variation in the length of genes can lead to different protein structures and functions.

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17
Q

What is a species?

A

group of organisms that can reproduce with each other to produce fertile offspring.

Example: Lions, tigers, and leopards are all different species of big cats.

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18
Q

What is a hybrid?

A

offspring of two individuals who are not the same species.
the offspring are infertile.

Example: A liger is a hybrid offspring of a male lion and a female tiger.

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19
Q

Taxonomy

A

the science of classifying living things

The science of classifying living things is called taxonomy.

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20
Q

What are the 8 levels of Linnaean classification?

A

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

He created 7 ‘levels’ of classification (which has now expanded to 8): domain, kingdom, phylum, class, order, family, genus, species.

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21
Q

What can be used to remember the 8 levels of Linnaean classification?

A

Mnemonic: dumb kids playing cricket on freeways get squashed.

This can be remembered with the mnemonic dumb kids playing cricket on freeways get squashed.

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22
Q

What is the ‘least alike’ level in Linnaean classification?

A

Domain

In this system, domain is the ‘least alike’ level.

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23
Q

What is the ‘most alike’ level in Linnaean classification?

A

Species

In this system, species is the ‘most alike’ level.

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24
Q

What is Linnaean classification system based on

A

based on similarities in obvious physical traits

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25
Q

What is evolution?

A

Evolution is the change in a species over generations.

It can lead to the creation of new species. A generation is the time between the birth of an individual and when that individual produces their own offspring.

26
Q

what is generation

A

the time between the birth of an individual and when that individual produces their own offspring.

27
Q

why do cells divide

A

to make more identical cells
to make gametes (sperm and egg cells)

28
Q

DNA replication

A

copying a DNA molecule to produce two identical DNA molecules

footnote:
loose nucleotides bind with 2 exposed strands of DNA
Every body cell has two copies of every chromosome before replication (one from mother and one from father)

29
Q

what are the strands of the unzipped DNA called?

A

original strand: parent
new strand: daughter

30
Q

homologous chromosomes

A

pair of chromosomes that have similar genes but not identical

31
Q

chromatic

A

one half of a duplicated chromosome

32
Q

Asexual reproduction

A

involving only one individual
no speem or egg cells
offspring are identical (clones to the parent)
mitosis is a method to reproduce asexually

33
Q

natural selection

A

mechanism of evolution
ensures that only the traits that help a species survive and reproduce get passed on to future generations

34
Q

selective agent

A

environmental factor that acts on population during natural selection

35
Q

population

A

group of organisms of one species that interbreed and live in the same place at the same time

36
Q

speciation

A

one species split into two of more seperate species

37
Q

adaptation

A

characteristics that helps an organism survive and reproduce in its environment become more common

38
Q

biotic and abiotic factor definition

A

what make up ecosystems
biotic: living things
abiotic: non living things

39
Q

what is natural selection dependant on?

A

variation in a populations genetics
inheritance, selection pressures, time, adaptation
(VISTA)

40
Q

phenotype

A

physical trait

41
Q

genotype

A

trait passed through genetics
unique sequence of DNA

42
Q

5 sources of evidence for evolution

A

fossil record
comparative anatomy
genetics and biochemistry
geographic distribution of species
embryology

43
Q

fossils

A

preserved remains of ancient organism

44
Q

divergent evolution

A

when species with a common ancerstor develop different traits over time

45
Q

homologous structures

A

same structure, different functions in organism

46
Q

convergent evolution

A

unrelated species evolve similar traits over time

47
Q

analogous structures

A

same function, different structured organisms

48
Q

comparative anatomy

A

science of comparing the physical structures of different species

49
Q

embryology

A

study of the development, structure and function of embryos

50
Q

what is meiosis

A

type of cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes
(mitosis but it happens twice)
two divisions, 4 cells are produced from 1
number of chromosomes is halved: each daughter cell is haploid - they have one copy of each chromosome

51
Q

haploid vs diploid

A

haploid cells contain only one set of chromosome (formed through meiosis)
diploid contain 2 sets of chromosomes

52
Q

crossing over in meiosis

A

when homologous chromosomes are pairing up (before metaphase) they connect together and swap genes

53
Q

purpose of crossing over

A

introduce variation into combinations of genes found in gametes

54
Q

what does sexual reproduction involve

A

the joining or fertilisation of sperm and egg cells. when the two haploid cells join they restore the diploid state

55
Q

homozygous

A

2 alleles are the same (RR or rr)

56
Q

heterozygous

A

2 alleles are different (Rr)

57
Q

punnett square

A

way of showing all the possible types of offspring

58
Q

how do we determine sex

A

if X sperm fertilised an egg =XX
if Y sperm fertilises an egg =XY

59
Q

4 steps of Speciation

A

variation
isolation
selection
isolation

60
Q

isolation

A

stops genes flowing between populations
initial population to be seperated into two or more populations that are unable to interbreed

61
Q

comparison of mitosis and meiosis

A

mitosis: pair of double stranded chromosomes line up, one double-stranded chromosome of each pair moves to each pole, two cells are formed
meiosis: four cells result with a haploid number of chromosomes, chromatids seperate and move to poles, double-stranded chromosomes line uo

62
Q

sex linkage

A

genes found in the sex chromosomes
x chromosome is longer than y chromosome

sem 2 science (2 decks)

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