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Science grade 9 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

What are sex cells

A

Also known as gametes, they have the chromosome of the parent cell. They make up a small part of the body

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2
Q

What are male gametes called

A

Sperm

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3
Q

What are female gametes called

A

Egg or ovum (ova plural)

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4
Q

What is meiosis

A

Process that produce gametes is called meiosis

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5
Q

Where does meiosis take place

A

Only in cells that produce gametes(reproductive cells)

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6
Q

Why is meiosis sometimes referred to as reduction deduction

A

Because it reduces the number of chromosome by half

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7
Q

What are haploid cells

A

Cells with half the chromosome number of the parent

Symbolized with a “n”

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8
Q

What are diploid cells

A

Cells with a complete set of chromosomes

Symbolized as 2n

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9
Q

What are homologous chromosomes

A

Diploid somatic cells have their chromosome arranged in pairs. Each chromosome has a corresponding one ,forming a pair. The pairs of corresponding chromosomes are called homologous chromosomes
Comes from parent
Each contributes half

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10
Q

What are somatic cells

A

Body cells that reproduce by cell division and make up the vast majority of the organisms cells
Has 23 pairs of chromosomes

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11
Q

What are the 2 stages of meiosis

A

Meiosis I and meiosis II

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12
Q

What is the end result of meiosis

A

4 haploid gametes

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13
Q

Explain meiosis I

A

Similar to mitosis during interphase and prophase
During interphase , chromosomes replicate to form joined sister chromatids
During prophase , chromosome shorten and thicken and become visible
Homologous chromosomes pair up along the equator during metaphase of meiosis I
During anaphase in meiosis I, the pairs of homologous chromosomes separate and move to opposite poles along with their sister chromatids .
Results in two daughter cells but each only has only one homologous chromosome with its sister chromatids still attached

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14
Q

Do sister chromatids separate in meiosis I

A

no

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15
Q

Explain meiosis II

A

sister chromatids in the 2 daughter cells line up at the equator of the cell Each chromatid is pulled to the opposite pole
The nuclear membrane reforms, cytokinesis occurs and results in 4 haploid cells called gametes

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16
Q

Tell some of the differences between mitosis and meiosis

A

In mitosis , sister chromatids separate during anaphase while in meiosis the sister chromatids separate in meiosis II
Mitosis results in 2 diploid cells while meiosis results in 4 haploid cells

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17
Q

What is fertilization

A

The joining or fusion of two gametes

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18
Q

What is a zygote and how is it formed

A

Zygote is the first diploid cell of the offspring and is produced by fertilization

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19
Q

How does the zygote increase in size

A

cell division

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20
Q

Will each new cell have the same DNA as the zygote

A

yes

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21
Q

what is diversity and what causes it

A

Vast amount of variation between species because of sexual reproduction because of homologous pairs

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22
Q

What are alleles and give examples

A

Different forms of the same gene

for example; eye colour, hair line and thumb

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23
Q

How does having homologous pairs produce variations in the gene

A

The corresponding gene for each chromosome might be slightly different .

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24
Q

When will a recessive allele be expressed

A

when both chromosomes contain the recessive allele

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25
When will a dominant allele be expressed
when present
26
What is expressed if the chromosome has both a recessive allele and a dominant allele
dominant allele
27
What is incomplete dominance and give an example
Is when neither one of allele gets to be dominant the two different alleles produce a mixture of traits for example red carnations give pollen to white carnations to make pink carnations
28
what is codominance and give an example
when both traits are expressed in one individual for example if a parent animal has red hair and the other has white , then the animal will have a roan colored coat mixture of white and red
29
Are some characteristics controlled by more than one gene or are have more than two alleles . If so give an example
yes like eye colour
30
What is the difference between sexual and asexual reproduction
asexual need one parent while sexual needs 2 | asexual reproduction can produce many identical offspring while sexual produce less and genetically different offspring
31
give one advantage and one disadvantage of sexual reproduction
Advantage is the variation helps them adapt to the changes in the environment and survive Disadvantage is that it is slow and requires two parents
32
give one advantage and one disadvantage of asexual reproduction
advantage is that it is faster and if the parent is successful in one environment then so is the offspring since genetically identical disadvantage is that if the environment changes , all are affected so less chances of survival
33
what is conjugation and explain the process . | give examples
occurs when two unicellular organisms transfer their gentic material It happens in bacteria and some protists like paramecium In conjugation, one cells copies an extra piece of its DNA, called a plasmid, and transfers the plasmid copy to another cell through the mating bridge They then reproduce asexually by binary fission
34
How does binary fission help unicellular organisms
Increases diversity
35
What is a hermaphrodite
an organism that produces both male and female sex cells in the same individual
36
What is the advantage of a hermaphrodite
Can mate with any other member of its own species and this make sexual reproduction easier
37
Give 2 examples of hermaphrodites and their process of reproduction
Earth worms produce both egg and sperm. When they encounter other earthworms , they exchange sperm with them. Sperm is stored in a special sac till eggs are ready . Fertilization takes place in the worm and each lays eggs Aquatic hermaphrodites like sponge and barnacles are fixed at one location. They produce egg and sperm at different times so that when the ocean current comes , the sperm doesn't accidently fertilize their own eggs as the result would be clones
38
Are flowers hermaphrodites
yes
39
What is the male reproductive structure in a flower
stamen
40
What is female reproductive structure in a flower
pistil
41
what is stamen made of
filament which is a stalk that supports the anther
42
Where is the anther and what does it do
At the top of stamen and produce pollen
43
Where are the male gametes in a flower found
In the pollen grains
44
What are sepals
tiny leaf like structures that protect the flower while it is in bud stage
45
Where is stigma and what do it do
Top of the tube like pistil and it receives a pollen grain since is sticky
46
What does the tube like style do
transfers the pollen grain from the stigma to the ovary
47
where are the eggs contained
ovary
48
What are petals and their function
coloured leaf like structures of flowers. Attracts pollinators
49
What is pollination
the process in which sperm cells(in the pollen) move to egg cells(in the ovary)
50
What are the two types of pollination and explain
In cross pollination , pollen is moved from the male structure of one flower to the female structure of another flower by using wind, insects , bird or mammals In self pollination , the pollen produced a flower can pollinate other flowers on the same plant
51
what follows pollination
fertilization
52
Does the zygote or fertilized egg develops into a seed in the ovary of the flower
yes
53
What are the two methods of fertilization in animals with separate sexes
External and internal fertilization
54
What happens in external fertilization and give examples
the sperm and the egg unite outside the body Fish is an example the female release her eggs in the water . then male releases his sperm over the eggs and produce a zygote
55
how is external fertilization risky and how do the animals compensate for it
The gametes and zygote both are vulnerable to predators and the environment. To ensure survival, thousand of eggs and sperm are released
56
What is internal fertilization and give an example
Sperm of the male is deposited inside the female using specialized reproductive structures . Example is some aquatic animals and most land animals
57
What is an embryo
When the zygote divides using mitosis, it forms an embryo | It is the developing organism
58
How are embryo protected
when inside the seeds, eggs or the mother
59
In plants ,what does the seed contains
embryo and stored food
60
In plants , what does the ovary becomes
Fruit
61
What is the egg called once it is fertilized
a seed
62
what nourishes the plant until photosynthesis
stored food in the seeds in form of starch
63
From which 3 seeds does most of the world's food comes from
corn , rice and wheat
64
What are cotyledons
seed leaves
65
What are dicotyledons and example
seeds with 2 seed leaves like bean plants
66
What are monocotyledons and example
seeds with only one seed leaves like corn
67
do the seeds use the food in the cotyledon when they germinate
yes
68
what is radicle
part of embryo that will develop into the roots
69
What does the epicotyl become
stem and the leaves
70
In corn seed , what supplies food
endosperm
71
in beans , what protects the epicotyl
the hypocotyl pushes up through the soil and protect the epicotyl
72
do cotyledons drop as the first leaves develop
yes
73
What is protecting the embryo in eggs
eggshell, jelly substance or an egg casing
74
What is an amniotic egg and give examples of some animals that lay them
Eggs of reptiles and birds | An amniotic eggs contains a single embryo surrounded by a shell
75
Name the structures of an amniotic cell
yolk sac, allantois, chorion , amnion , embryo , albumen and air space
76
What is the purpose of the yolk sac
stores food for the embryo
77
What is the purpose of the allantois
holds the waste produced by the embryo
78
What is the purpose of the chorion
controls the movement of the gases and waste in and out of the egg so does the allantois
79
What is the purpose of the amnion
a fluid filled sac which cushions the embryo
80
What is the purpose of the the albumen
cushions the embryo and is an additional food source
81
how do birds protect their eggs
they incubate them(keep at a certain temp by sitting on them) to develop them
82
how do reptiles protect their eggs
lay and abandon eggs in a climate that will develop them
83
What are monotremes and their 3 species
mammals that lay eggs duck bill platypus two types of spiny ant eaters
84
What are marsupials and examples
have embryos that do not develop inside the mothers uterus . the young are born . they leave the birth canal , climb through the mom's fur and enter a pouch where they attach to a nipple of the mammary gland. They grow and develop their examples are kangaroos, koalas and opossums
85
What are placental mammals
embryos develop inside the mammal
86
What is placenta
organ that develops around the fetus and connects to the mother
87
What connects the fetus to the mother and what is its function
the umbilical cord carries the waste out of the fetus and nutrients to the fetus
88
Explain selective breeding and give an example
In selective breeding 2 plant or animals of one species that have desirable traits are bred with each other . The breeder then selects the offspring with desirable traits and breds it with other offspring with the same desirable traits . After several generations , all the offspring will have this trait . Example canola plants and beef cattle
89
Explain artificial vegetative reproduction and give examples
Uses plants ability to reproduce vegetatively produces clones Individual cells from desirable plants are removed and placed in petri dishes with nutrients and growth hormones . Once they have roots , they are planted in soil
90
Explain grafting
Takes a branch from a desirable fruit tree and attach it to the trunk of another tree that has excellent roots but poor fruit. This produces varieties of fruits
91
What is artificial insemination
used in agriculture to fertilize domestic animals used by people when trouble conceiving sperm collected from desired male and frozen , then inserted in female vagina after ovulation days
92
Explain In Vitro fertilization
The sperm and several eggs are collected from male and female animals and fertilization occurs in petri dish Once eggs are fertilized they can inserted in many different females to grow
93
What is an advantage of In Vitro fertilization
Produces many more embryos than naturally produced
94
What do fish hatcheries do
If the male and female are caught before spawning , their eggs and sperm are collected and mixed together in a container . Then the fertilized egg is incubated until they hatch and then released
95
What are surrogate mothers
Not genetically related to the embryo
96
What is recombinant DNA technology
Involves combining genes from different individuals or species into a single molecule of DNA Human growth hormone to cure dwarfism is now extracted from bacteria with recombinant DNA instead of the pituary glands of dead people
97
What are GMO's
Genetically modified organisms
98
Why are many food crops genetically modified
to resist spoilage resist disease delay ripening more nutritional content
99
What are some concerns related to GMO's
can their modifications to wild populations will their be any original organism left who owns them
100
Give examples of GMO's
corn and pigs

Science grade 9 (5 decks)

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