Chapter 7 Flashcards
1
Q
The nucleus of every cell contains threads called_______
A
chromosomes
2
Q
What condition must be used to look at chromosomes
A
using a light microscope when a cell is dividing.
3
Q
Chromosomes need to be coloured using what in order to be able to see them?
A
special stains
4
Q
Different organism have different numbers of chromosomes in the nuclei of their cells.
True of False?
A
True
5
Q
How much chromosomes do human cells have?
A
46 chromosomes
6
Q
What is the longest chromosome in a human cell?
A
Chromosome 1
7
Q
Why do chromosomes look like cross shape
A
before the cell divides, each chromosome makes a copy of itself and the two copies stay joined together part-way along their lenght.
8
Q
What is chromosome made up of?
A
Each chromosome is made up of hundreds of different genes.
9
Q
How are the genes arranged in a chromosome?
A
The genes are arranged in a particular sequence along the chromosome.
10
Q
What are the function of genes
A
each gene helps control a particular characteristic in the organism.
11
Q
Draw an example diagram of a short chromosome with stripes representing genes
A
pg 245
12
Q
Does the amount of genes get lower as the chromosomes get shorter?
A
Yes
13
Q
Does Chromosome 1 or Chromosome 15 have more genes and why?
A
Chromosome 1 has more genes than chromosome 15 because it is longer.
14
Q
do genes determine eye colour?
A
yes
15
Q
Chromosomes are made a chemical substance called what?
A
DNA
16
Q
Each chromosome is one enormously long molecule of DNA
True or False?
A
True
17
Q
Genes are also made of DNA
true or false?
A
true
18
Q
A DNA molecule has a shape like what?
A
twisted ladder
19
Q
What is the Shape of DNA molecule called?
A
double helix
20
Q
Can we see twists when when we use microscopes to look at chromosomes? Why?
A
No, this is because DNA molecules are much too small to see
21
Q
When was DNA first discovered?
A
in 1950s
22
Q
What does the DNA in a cell determine?
A
It determines what the cell does.
23
Q
What does DNA contain?
A
It contains a complete set of instructions to make a functioning cell, and a whole organism.
24
Q
Every human being began life as a single cell, how was this cell formed?
A
It was formed when a sperm cell joined with an egg cell.
25
Sperm cells and egg cells are specialised cells known as what?
Gametes
26
What are gametes?
specialised cells
27
What type of gamete is a sperm cell?
male gamete
28
What typ of gamete is an egg cell?
female gamete
29
Draw a sperm cell and label it
pg 248
30
What do sperm cell contain?
tail that produces swimming movements
cell surface membrane
nucleus containing 23 chromosomes
small amount of cytoplasm
31
How many chromosomes are there in the nucleus of a sperm cell?
23 chromosomes
32
What type of microscope is used to scan egg and sperm cells?
scanning electron microscope
33
What structures does the egg cell contain?
cell surface membrane
cytoplasm containing food reserves
nucleus containing 23 chromosomes
34
How many chromosomes are in a nucleus of an egg cell?
23
35
Can egg cells move by itself?
no
36
Why do egg cells need to be larger than sperm cells?
They contain food reserves
37
Describe the size of an egg cell
same size as a full stop
38
how many set of chromosomes do gametes have?
only 1 set
39
What is fertilisation?
The joining of a sperm cell with an egg cell
40
What will happen if the head of sperm cell enters the egg cell?
nucleus of the sperm cell and nucleus of the egg cell fuse together.
41
What is a zygote?
The new cell that is formed when the nucleus of the sperm cell and the egg cell join together.
42
What are sex chromosomes
chromosomes that determine whether a person is male or female.
43
What sex is a person with two X chromosomes (XX)
XX is a female.
44
Is Y chromosome or X chromosome smaller
Y chromosomes are much smaller than X chromosomes.
45
What sex is a person with one X chromosome and one Y chromosome?(XY)
XY is a male
46
What sex chromosomes do all egg cells have?
All egg cells contain one X chromosome.
47
What type of sex chromosomes do all sperm cells have?
Sperm cells can have either one X chromosome or one Y chromosome.
48
Zygote with two X chromosome(X-containing sperm cell) will become?
a baby girl
49
Zygote with Y-containing sperm cell will become?
a baby boy
50
What does the term Inheritance mean?
passing on DNA from parents to offspring
51
What is the term sex inheritance used to describe?
It is used to describe a baby's sex is determined because a baby inherits X or Y chromosomes from its parents.
52
The differences between individuals belonging to the same species are called___
variation
53
How can genes in sperm cells and egg cells of goat affect the development of horns?
Different version of genes might produce long horns, another short horns and another one with no horns at all.
There could also be different genes for making curved horns or straight horns.
54
What do genetic differences mean
differences in the DNA of organisms within a species
55
everyone in a family has a slightly different combination of DNA from everyone else.
There are genetic differences between them.
True or False?
True
56
When a sperm cell and egg cell fuse together at fertilisation, the zygote that is produced has a new combination of DNA, which is not exactly the same as in its parents , or in its brothers and sisters.
True or False?
True
57
Does the environment affect the DNA of an organism?
Yes, it does
58
Two adult goats with different coat colours, this is determined by what?
And the variation in coat colour is caused by what?
It is determined by their DNA, and the variation in coat colour is caused by genetic differences.
59
Give an example how the size of goat could be affected by DNA but by its environment at the same time.
One goat might eat more than another, so it would grow fatter and have a greater body mass.
60
Not all variation within a species is caused by differences in DNA.
True of False?
True
61
What is the theory that almost every species is well adapted to its environment?
1. There is variation among individual organisms in every species
2.Some of this variation is caused by differences in their genes
3. Some individuals have features that make it more likely that they will survive than individuals that do not have these features
4. The individuals with advantageous features are more likely to reproduce, pass on the genes that produce the advantageous features to their offspring.
5.Over many generations, the genes that produce advantageous features get more common, and the genes that are not so useful get less common.
62
1. There is variation among individual organisms in every species
2.Some of this variation is caused by differences in their genes
3. Some individuals have features that make it more likely that they will survive than individuals that do not have these features
4. The individuals with advantageous features are more likely to reproduce, pass on the genes that produce the advantageous features to their offspring.
5.Over many generations, the genes that produce advantageous features get more common, and the genes that are not so useful get less common.
What process is this called?
Natural Selection
63
What is an example of natural selection in microorganisms?
Antibiotics and medicinal drugs that we can take to cure diseases caused by the bacteria.
Doctors found out that some antibiotics do not work anymore and bacteria has become resistant to them.
64
In a population of bacteria, not every one is alike.
True or False?
True
65
In a population of bacteria, one may have a gene that makes it resistant to an antibiotic.
True of False?
True
66
can the resistant bacteria can multiply and form a population of resistant bacteria after antibiotic is added which kills the bacteria that are not resistant?
Yes, it can
67
Give an example of natural selection in peppered moths.
Peppered moths fly at night and spend the daylight hours resting on tree trunks, they are hunted by birds.
The pale colour of peppered moths camouflages them perfectly against lichen-covered tree bark.
Dark coloured peppered moths were not well hidden on the lichen-covered tree trunks.
Pale colour peppered moths are more likely to survive and pass on their advantageous genes.
Over time, pale colour peppered moths became more and more common
68
What is a complex that contains DNA?
chromatin
69
what do eukaryotic cells mean?
animal and plant cells.
70
Chromosomes are found in the nucleus of eukaryotic cells.
true or false?
True
70
How many PAIRS of chromosomes are in humans?
23
71
In Sex Chromosomes and Autosomes, how many chromosomes are there for both?
2 Sex chromosomes and 44 chromosomes for Autosomes
71
What 2 different types of chromosomes are there?
Sex chromosomes
Autosomes(non-sex chromosomes)
71
How many pair of chromosomes are in fruit flies?
4 pairs
71
What are homologous chromosomes?
matching pairs of chromosomes?
72
Describe the structure of a chromosome
1. The 2 legs above are short
2. The 2 legs below are long
3. contains gene that contains segment of DNA that codes a trait
4.2 strands of chromatids
5. Centromere(middle part) that holds 2 chromatids together
73
Describe homologous chromosomes.
-similar in structure and composition
-same genes on same locus
-may have same or different alleles
74
What is a Homologue?
a member of each pair of homologous
75
give 1 fact about Homologue
Either maternal or paternal
76
what is a maternal homologue?
one chromosome from a pair that is received from mother.
77
what is paternal homologue?
one chromosome from a pair that is received from father.
78
How can homologous chromosomes be distinguished?
- similiar bonding pattern after staining
-similar centromere's position
-Similar shape and size of chromosome
79
The DNA was founded by who?
Watson and Crick
80
What is a factor that an allele can determine?
hair colour
81
State the difference between sperm and egg cells
Sperm cell:
has a tail
smaller cell
can move
does not contain food reserves
sex cell produced by males
Egg cell:
is more round
does not have a tail
larger
cannot move
contain food reserves
sex cells produced by females
82
Give 5 examples of variation in humans
1. eye colour
2. hair types (wavy/curly/straight)
3. Shoe size
4. ear lobes
5.ability to roll their tongue
83
