biology exam revision

Question 1

what is inheritance?

Answer 1

the study of how genes are passed from parents to offspring

Question 2

who discovered inheritance?

Answer 2

Gregor Mendel

Question 3

what is a dominant allele

Answer 3

an allele that masks/hides recessive alleles

Question 4

what is a recessive allele

Answer 4

A allele that is only seen in the absence of a dominant allele

Question 5

what is an allele

Answer 5

a variation of a gene

Question 6

what is a gene?

Answer 6

A small segment of DNA that controls what characteristics an organism has.

Question 7

what does DNA stand for?

Answer 7

Deoxyribo nucleic acid.

Question 8

what makes up a nucleotide?

Answer 8

one phosphate, one deoxyribose sugar and one nitrogenous base.

Question 9

In diagrams on a nucleotide, what shape normally represents the phosphate?

Answer 9

the circle

Question 10

In diagrams on a nucleotide, what shape normally represents the deoxyribose sugar?

Answer 10

A pentagon

Question 11

In a DNA ladder… what makes up the steps?

Answer 11

nitrogenous bases

Question 12

Where is DNA located in a cell?

Answer 12

the nucleus

Question 13

When DNA is loosely condensed and wrapped into a wool like structure what is it called?

Answer 13

chromatin

Question 14

When DNA is tightly condensed and packaged. What is it called?

Answer 14

chromosome

Question 15

How many chromosomes are in a normal human cell?

Answer 15

46 chromosomes

Question 16

How do nitrogenous bases bond together?

Answer 16

via hydrogen bonding

Question 17

how many nitrogenous based are there?

Answer 17

4

Question 18

What are the four letter that represent nitrogenous bases?

Answer 18

A, T, C, G

Question 19

What is the name of the nitrogenous base A?

Answer 19

Adenine

Question 20

What is the name of the nitrogenous base T?

Answer 20

Thymine

Question 21

What is the name of the nitrogenous base C?

Answer 21

Cytosine

Question 22

What is the name of the nitrogenous base G?

Answer 22

Guanine

Question 23

Which bases pair together?

Answer 23

A and T

C and G

Question 24

What makes up the backbone of DNA?

Answer 24

Phosphates and deoxyribose sugars

Question 25

what is the purpose of DNA replication?

Answer 25

To create multiple copies of identical DNA

Question 26

What are the 3 stages of DNA replication

Answer 26

1. straightening and separating of DNA (denaturation) 2. cloning (DNA synthesis) 3. Checking for errors

Question 27

What occurs in the first stage of DNA replication?

Answer 27

-An enzyme breaks apart the hydrogen bonds between the nitrogenous base pairs. -The two DNA strands separate and unwind -This exposes the nitrogenous bases

Question 28

hat occurs in the second stage of DNA replication?

Answer 28

-In the nucleus there is free floating nucleotides -The free floating nucleotides bond to the exposed nitrogenous bases (hydrogen bonding) -An enzyme binds the DNA backbone backbone in the new DNA strand -This creates 2 new DNA strands that are identical. (They both have 1 of the original strand and 1 of the newly made strand)

Question 29

What occurs in the third stage of DNA replication?

Answer 29

An enzyme proof-reads that DNA strand and checks for any errors. Any errors are fixed.

Question 30

What is the centre part of a chromosome called?

Answer 30

A centromere

Question 31

How do you count chromosomes?

Answer 31

by the number of centromere

Question 32

What is half a chromosome called?

Answer 32

a chromatid

Question 33

Two chromatids that join in the middle can be called what?

Answer 33

sister chromatids

Question 34

Chromosomes can be single stranded or double stranded.. how many copies of DNA are in each type?

Answer 34

ingle- 1 copy double- 2 copies

Question 35

What is a karyotype?

Answer 35

A picture of all the chromosomes in an organism's genome

Question 36

In a human karyotype, the first 22 chromosome pairs are...?

Answer 36

autosomal -determine general traits

Question 37

In a human karyotype, the 23rd/last chromosome are...?

Answer 37

sex chromosomes

Question 38

What are male sex chromosomes?

Answer 38

XY

Question 39

What are female sex chromosomes?

Answer 39

XX

Question 40

What occurs is pre- mitosis?

Answer 40

interphase

Question 41

What occurs in interphase in mitosis and meiosis one ?

Answer 41

-DNA replicates -single stranded chromosomes become double. -Chromatin become visible.

Question 42

What occurs in prophase of mitosis and meiosis?

Answer 42

The nuclear membrane breaks down -spindle fibres appear -Chromatin condense into chromosomes

Question 43

What occurs in metaphase of mitosis?

Answer 43

-chromosomes line up in the equator of the cell -Spindle fibres attach to the centromere of chromosomes

Question 44

What occurs in metaphase of meiosis 1?

Answer 44

-Homologous chromosome pairs line up in two lines along the equator of the cell -Spindle fibres attached to chromosomes.

Question 45

What is the difference between metaphase 1 and metaphase 2 of meiosis?

Answer 45

In metaphase 1, Homologous chromosomes line up in pairs along the equator. whereas, In metaphase 2, a single line of doubles stranded chromosomes lines up along the equator.

Question 46

What occurs in anaphase of mitosis?

Answer 46

-The spindle fibres contract/shorten -The double stranded chromosomes are ripped apart into single stranded chromosomes (chromatid). - The chromatid move to opposite poles of the cell

Question 47

What is the difference between anaphase 1 and 2 in meiosis?

Answer 47

In Anaphase 1, spindle fibres separate a homologous chromosome pair. One double stranded chromosome moves to each pole of the cell. whereas, -In Anaphase 2, spindle fibres rip apart a double stranded chromosome into single stranded chromosomes (chromatid). one chromatid moves to opposite poles of the cell.

Question 48

what occurs in telophase during mitosis and meiosis?

Answer 48

Two new nuclear membranes are formed -Spindle fibres disappear - chromosomes unwind into chromatin

Question 49

What occurs during cytokenesis?

Answer 49

The cytoplasm pinches in half and becomes 2 separate cells.

Question 50

What phase occurs in meiosis 1 and not meiosis 2?

Answer 50

interphase

Question 51

Why are gametes haploid?

Answer 51

so that when they fuse during fertilisation, they become diploid.

Question 52

What does haploid mean?

Answer 52

A cell with 1 copy of DNA

Question 53

What does diploid mean?

Answer 53

A cell with 2 copies of DNA

Question 54

What types of cell does mitosis produce?

Answer 54

diploid

Question 55

What types of cell does meiosis produce?

Answer 55

haploid

Question 56

Are cell produced from mitosis identical or genetically different?

Answer 56

identical

Question 57

Are cell produced from meiosis identical or genetically different?

Answer 57

genetically different

Question 58

What is the purpose of meiosis?

Answer 58

Sexual reproduction -producing gametes

Question 59

What is the purpose of mitosis?

Answer 59

What is the purpose of mitosis?

Question 60

How many cells are created from mitosis?

Answer 60

2

Question 61

How many cells are created from meiosis?

Answer 61

4

Question 62

what times do cell spend the most time in?

Answer 62

interphase

Question 63

What is the difference between mitosis and cytokenesis?

Answer 63

-mitosis is the separation of the nucleus whereas, -cytokinesis is the separation of the cytoplasm/cell