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Reproduction and Growth Flashcards

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1
Q

What does mitosis do?

A

Produces genetically identical daughter cells, these cells are diploid (they have one pair of each chromosome in each nucleus)

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2
Q

How many PAIRS of chromosomes do human diploid cells have?

A

Human diploid cells have 23 pairs of chromosomes (46 in total)

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3
Q

What is mitosis used for?

A

Growth, repair and asexual reproduction

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4
Q

What does meiosis do?

A

Produces haploid gametes (sperm, eggs and pollen) which are NOT genetically identical

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5
Q

How many chromosomes UNPAIRED do human haploid cells have?

A

23 chromosomes in total (unpaired)

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6
Q

What is meiosis used for?

A

Only used to produce gametes for sexual reproduction

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7
Q

What is the consequence of meiosis?

A

Every gamete produced is genetically different, it carries different alleles to every other gamete

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8
Q

What is the variation in offspring in meiosis produced by?

A

-genetic variation in gamete cells produced by meiosis
-random fertilisation of ova (egg cells) by male gametes

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9
Q

What are the differences in the processes of mitosis and meiosis?

A

Mitosis:
-produces genetically identical daughter cells
-produces two cells
-involves one division
-produces diploid cells in humans
-keeps the same chromosomes number

Meiosis:
-produces genetically non-identical daughter cells
-produces four cells
-involves two cell divisions
-produces haploid cells in humans
-halves the number of chromosomes

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10
Q

What are the differences in the roles of mitosis and meiosis?

A

Mitosis:
-generates all adult cells except gametes (growth and repair)
-occurs throughout the human body
-occurs throughout a plant
-used for asexual reproduction (cloning)

Meiosis:
-only used to produces gametes
-only occurs in ovary and testis
-only occurs in ovary and anther
-used for sexual reproduction

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11
Q

What type of cell division is mitosis?

A

Mitosis is a type of cell division in which a diploid body cell copies itself and finally divides into two identical diploid daughter cells, the daughter cells are clones of each other, every base pair of their DNA is identical

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12
Q

What are the stages of mitosis?(5)

A

-the cell grows
-DNA replicates to form two copies of each chromosome, these copies (chromatids) are joined at a single point (the centromere)
-nuclear membrane breaks down, chromosomes line up across the centre of the cell, attached to special spindle fibres
-chromatids (replicas) are pulled apart and move to opposite ends of the cell
-cytoplasm and cell membrane divides to form two identical cells

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13
Q

What type of cell division is meiosis?

A

Meiosis is the type of cell division which gives rise to cells that are genetically different

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14
Q

Where does meiosis take place?

A

Sex organs

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15
Q

Why are gametes different from other cells?

A

They have half the normal number of chromosomes (they are haploid)

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16
Q

Why will offspring in meiosis differ from their parents?

A

Maternal and paternal chromosomes meet in different combinations in the zygotes, consequently the offspring will differ

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17
Q

How many genetically different haploid cells does meiosis produce?

A

4

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18
Q

What are the stages of meiosis?(6)

A

-the parent cell grows
-DNA replicates to form two copies of each chromosome, these copies (chromatids) are joined together at a single point (the centromere)
-nuclear membrane breaks down, homologous pairs of chromosomes join together
-homologous pairs of chromosomes exchange sections of DNA, then they attach to the spindle fibres in pairs at the centre of the cell
-homologous pairs of chromosomes are pulled apart and move to opposite ends of the cell, the cells divides
-chromosomes line up along the centre of the cell, attached to the spindle fibres, the chromatids separate and move to opposite ends of the cell, each cell divides again

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19
Q

What is the tail-like thing called on a sperm?

A

Flagellum

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20
Q

What do some male animals like fish do?

A

Release their sperm into the water in which they live

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21
Q

How often are egg cells produced in female humans?

A

Monthly

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22
Q

When do males start producing their sperm?

A

In puberty and will continue to do so

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23
Q

Are women born with all of their eggs?

A

Yes

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24
Q

What is external fertilisation?

A

In fish, the female releases their ova into the water and the sperm have to swim through the water to fertilise the ova, this kind of fertilisation takes place outside the body so it’s called external fertilisation

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25
What is internal fertilisation?
Other male animals including birds and mammals, ejaculate their sperm in a special fluid (semen) into the bodies of the females during sexual intercourse, this happens on the inside of the body so it’s called internal fertilisation
26
How many chromosomes are in a normal human body cell (with an exception of red blood cells and gametes)?
46 chromosomes, consists of 23 pairs of homologous chromosomes containing the same genes
27
Where does the two sets 23 chromosomes in the body cell originate from?
The organism’s father (sperm cell) and the mother (egg cell or ovum)
28
As the cell has two sets of chromosomes (maternal and paternal), what is it known as?
Diploid cell
29
In a human, how many chromosomes each does the sperm an ova have?
23 chromosomes
30
What are cell with half the genetic information known as?
Haploid cells
31
What is it called when a haploid sperm and a haploid cell fuse together?
Fertilisation has occurred to form a diploid cell
32
What is the first cell that is formed at fertilisation known as?
A zygote
33
As each gamete has only half the normal number of chromosomes, how many does a zygote formed by fertilisation have?
The full number of chromosomes
34
What is fertilisation?
Fusion of haploid male and female gametes, restoring the diploid number of chromosomes in the zygote
35
What is the ovary and what does it do?
-egg cells are formed by meiosis (in the follicle) -produces hormones oestrogen and progesterone
36
What is the oviduct and what does it do?
-egg cells travel down this to the uterus -lined with cilia, which move the cell -site of fertilisation
37
What is the uterus and what does it do?
-womb -lining forms in the uterus -embryo will implant here -foetus develops in the uterus, which has a thick muscular wall that contracts during labour
38
What is the cervix and what does it do?
-narrow opening to the uterus -dilates (widens) during labour to allow baby to be born
39
What is the vagina and what does it do?
-muscular tube that leads from the cervix to the outside of the woman’s body -man’s penis is goes into the woman’s vagina during sexual intercourse -baby passes through vagina when it is born
40
What is the testes and what does it do?
-sperm cells are formed by meiosis -produces the hormone testosterone
41
What is the sperm duct and what does it do?
-maturing sperm are transported along this tube
42
What is the seminal vesicles and prostate gland and what does it do?
-releases liquid into the sperm duct, which mixes with the sperm cells to form semen -liquid provides nutrients to the sperm
43
What is the penis and what does it do?
-transports urine and semen out of the body -contains tissue which fills with blood to become erect (help to pass semen out the body and into females vagina during sexual intercourse)
44
What is the urethra and what does it do?
-tube inside the penis, which can transport either urine or semen
45
What does the sperm do during sexual intercourse?
Sperm pass along the sperm duct and are mixed with a fluid from the seminal vesicles (this mixture is called semen) and is ejaculated into the vagina of the female out if the urethra, sperm then begin to swim towards the oviducts (also known as fallopian tubes)
46
What causes the random fertilisation to have genetic variation in offspring?
-each male ejaculate will contain millions are sperm that are all genetically different due to meiosis -each female egg will also be genetically different due to meiosis -the sperm cell that fertilises the egg cell is random -the “randomness” causes variation in the genetics of the new offspring
47
What hormone does the placenta secrete and why?
Progesterone to ensure uterus lining remains thick and to prevent the embryo from aborting
48
What does the membrane amnion do and secrete?
Amnion encloses the developing embryo, it secretes a fluid called amniotic fluid which -protects the developing embryo against jolts and bumps -drying out -temperature fluctuations
49
What is the embryo called when it starts to look human?
Foetus
50
What does the placenta allow when anchoring the embryo in the uterus?
-nutrients (e.g. glucose, amino-acids, salts and oxygen) to move from the mother to the embryo -metabolic wastes (carbon dioxide and urea) to move from the embryo to the mother These materials pass from one to the other by diffusion
51
Why is there no physical connection between the circulatory systems of the embryo to the mother, so their blood doesn’t mix?
-mothers blood is much higher pressure than the fetal blood -mothers blood has white blood cells and other chemicals that would see the fetal blood as foreign and attack it
52
What is the hormone involved in male puberty?
Testosterone
53
What is the hormone involved with female puberty?
Oestrogen
54
What are features for the male development of secondary sexual characteristics?(7)
-voice breaks -sperm production begins -shoulders broaden -facial, armpit, body and pubic hair growth -greater muscle development -growth and development of genitalia (penis) -possible mood swings and acne
55
What are features for female development of secondary sexual characteristics?(7)
-voice deepens, but doesn’t break -menstrual cycle begins -pelvis broadens in preparation for pregnancy and labour -armpit and pubic hair growth -muscle development and fat deposits on breasts, hips and thighs -growth of development of genitalia -possible moods swings and acne
56
How does the menstrual cycle begin?
Breakdown and loss of the uterine lining
57
When the menstrual cycle begins, what hormone production is increased by the pituitary gland?
The pituitary gland begins to produce increasing amounts of the hormone FSH
58
What does the increased production of FSH tell the ovary?
Tells the ovary to form a mature egg cell, a follicle develops with the maturing egg inside it, the follicle produces the hormone oestrogen
59
What hormone causes the lining of the uterus to thicken after the menstruation cycle?
Oestrogen
60
What happens as oestrogen levels rise?
As oestrogen levels rise, the stop of FSH production and trigger LH production in the pituitary gland
61
What does the hormone LH do?
LH stimulates ovulation, the release of the mature egg from the ovary
62
After the mature egg is released where does it travel?
Travels down the oviduct (fallopian tube) to the uterus, fertilisation takes place in the oviduct if sexual intercourse has taken place
63
What is left of the follicle that developed the maturing egg inside it after it releases the mature egg?
Forms a structure in the ovary called the corpus luteum, which makes another hormone called progesterone, later in pregnancy the placenta secretes progesterone (taking over the role of corpus luteum)
64
What is the first sign that a woman is pregnant?
When her monthly period stops
65
What is the main function of the menstrual cycle?
To control the development of the lining of the uterus (womb), so that if the ovum is fertilised, the lining will be thick and ready to receive the fertilised egg
66
What is the lining lost from the uterus in a woman’s body as the flow of a menstrual cycle called?
A period
67
What are the four hormones called that the timing of events in the menstrual cycle is controlled by?
-FSH -oestrogen -LH -progesterone
68
What two ways can plants reproduce (like animals)?
Sexually and asexually
69
What is reproduction?
The ability of living organisms to produce offspring
70
What does sexual reproduction produce?
Produces genetically varied offspring using specialised sex cells called gametes
71
What are the two advantages of sexual reproduction?
-advantage in a changing environment -advantage when there is a threat of disease from pathogens
72
What are the three steps that need to occur for a new plant to be produced by sexual reproduction?
1)pollination 2)fertilisation 3)germination
73
What is the sexual organ of a flowering plant?
Its flowers, which are sites of pollination and fertilisation
74
What does asexual reproduction produce?
Produces genetically identical offspring (the offspring are called clones), gametes are not needed and only one parent is involved
75
What is an advantage of asexual reproduction?
-advantage in a stable environment because it allows parent plants with advantageous adaptations to produce offspring with the same beneficial characteristics
76
What ways can a plant asexually reproduce?(3)
-runners> a new plant is produced where the runner touches the ground -tubers> swollen underground stems containing lots of stored food one plant can produce many tubers which ca each grow many shoots which form new plants -bulbs> underground bulbs with thick fleshy leaved containing stored food, a main shoot will grow out of the parent bulb and another will grow out of the side “daughter” bulb, forming two plants
77
What is an artificial method of growing plants?
Cuttings- a piece of the plant’s stem, with a few leaves attached is cut from a healthy plant and planted in damp compost (where it will grow roots and develop into a new plant)
78
What are the three main functions of flowers as they are the sex organs of plants?
-production of gametes -sites of pollination and fertilisation -sites of seed and fruit formation
79
What is pollen and where is it produced?
Pollen is a gamete and is produced in the anther, which is part of the male part (stamen) of the flower
80
What is the ova and where is it produced?
Ova is a gamete produced by the ovules found in the ovary within the female part (carpel) of the flower
81
What is cross-pollination?
Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on another plant
82
What is self-pollination?
Self-pollination is where the pollen doesn’t need another plant, this is less commonly seen
83
What adaptations are on an insect-pollinated flower?
-stamens> enclosed within flower -stigma> enclosed within flower and sticky -petals> large and brightly coloured -nectaries> present (produce sugary fluid to attract insects)
84
What adaptations are on a wind pollinated flower?
-stamens> exposed outside of petals -stigma> exposed outside of petals, often “feathery” -petals> small, usually green -nectaries> absent
85
What is the specialised sex cell called that are produced in sexual reproduction?
Gametes
86
What are the 8 steps in pollination/fertilisation for a plant to create a fruit?
-pollen grains are deposited onto the stigma -pollen grain normally grows a pollen tube which grows down through the style -enzymes are secreted at the tip of the tube which digest the tissues of the style -when the tube reaches an ovule, male gamete travels through the tube entering ovule through a small hole called the micropyle -fuses with the female gamete (ovum) in the process of fertilisation -fertilised ovum divides by mitosis to form the embryo -ovule develops into the seed -ovary develops into a fruit
87
When two gametes fuse (fertilisation), it forms a single cell called what?
A zygote
88
What does a zygote divide by many times to form all the cells of the new organism?
Mitosis
89
What does a zygote develop into during fruit formation?
An embryonic plant with a small root (radicle) and shoot (plumule)
90
What does the ovule wall become during fruit formation?
The seed coat (hard coating of the seed)
91
What does the ovary wall become in fruit formation?
The fruit coat
92
Germinating seeds take a great deal of energy quickly, what do they use their food stores as?
They use their food stores using enzymes that break down carbohydrate stores
93
What three things do plants need to germinate?
-oxygen> to aerobically respire -warmth> optimum temperature for enzymes -water> to activate the enzymes

Biology (7 decks)

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