Biology  by Bradford
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D3.1 Reproduction: revision map

The subtopic in the middle and 14 tasks round it: label six diagrams, complete three tables, put three processes in order and fill 70 gaps. Every standard level statement has a box; the five boxes for higher level only are dashed and badged HL, and drop off for an SL class. Type into the blanks and check them, or print it on A4, Letter or A3 with an answer key.

D3.1 practice questionsThe whole D3 map

D3.1

Reproduction

1 of 2Organisms · Continuity and changeName

D3.1.4The female system

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About once a month an egg is released from a follicle: . If it is fertilized, the embryo develops in the , whose muscular wall contracts to push the baby out at .

D3.1.5, D3.1.7One cycle, four hormones

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Late in the first half, a high level of an ovarian hormone triggers a surge of the pituitary hormones by feedback. After the egg is released, the empty follicle becomes the , and its hormones hold the pituitary hormones down by feedback. IVF suspends this natural cycle, then high hormone doses cause .

D3.1.4The male system

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Sperm and the fluid added to them leave together as , through the . The fluid holds sugar for the sperm to respire and is , protecting sperm from the acid of the vagina.

D3.1Reproduction

D3.1.6Fertilization in humans

Number the steps in order.

  1. The sperm nucleus enters the egg; the sperm's tail and mitochondria are destroyed.
  2. The membranes round the sperm and egg nuclei break down.
  3. The sperm's cell membrane fuses with the egg's cell membrane.
  4. The condensed chromosomes from both gametes gather on one spindle.
  5. A joint mitosis produces two diploid nuclei: the embryo has two cells.

Each gamete brings one set of 23 chromosomes.

D3.1.1, D3.1.2, D3.1.3Asexual or sexual?

AsexualSexual
Gametesnonemade by , then fused at
Offspringgenetically identical to the parentnew combinations of
Best when the environment isstable, and the parent already well adapted to it, as variation lets some offspring adapt

The male gamete travels to the female gamete, so it is much , with fewer , and is made in far greater numbers.

D3.1.9, D3.1.10, D3.1.11Built for insects

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Animals or carry pollen between plants. Plants promote cross-pollination: male and female parts ripen at , or sit in separate flowers or on separate plants, and in many species genetic stops a plant fertilizing itself. Self-pollination would mean , which lowers genetic diversity and vigour.

D3.1.8, D3.1.12From pollen to seedling

Number the steps in order.

  1. A tube grows from the pollen grain down the style to an ovule.
  2. The zygote grows into an embryo, and the ovule becomes a seed.
  3. A male gamete from the tube fuses with the female gamete in the ovule.
  4. Animals, wind or water carry the seed away from the parent plant.
  5. The seed absorbs water, stored food is mobilized, and the embryo grows into a seedling.
  6. An insect carries pollen to the stigma of a flower on another plant.

Carrying pollen is ; carrying seeds away from the parent, which cuts competition, is .

Word bank alkalineallelesantherbirthcervixchangingcorpus luteumdifferent timesdispersalendometriumepididymisfertilizationfood reservesFSHhaploidinbreedingLHmeiosisnectarynegativeoestradiolovaryoviductovulationpetalpollinationpositiveprogesteroneprostate glandself-incompatibilitysemenseminal vesiclesmallersperm ductstigmasuperovulationtestisurethrauterusvaginawind
D3.1

Reproduction

2 of 2Organisms · Continuity and changeName

D3.1.14Making sperm and eggsHL

SpermatogenesisOogenesis
Gametes per meiosisone, plus small polar bodies
Cytoplasmshared equally; most is lost as the sperm formshared , so the egg keeps nearly all of it
Gametes releasedhuge numbers, continually from pubertyusually a month, from puberty to menopause

Both begin with , then cell growth, the two divisions of meiosis and finally .

D3.1.15, D3.1.16Fertilization to implantationHL

Number the steps in order.

  1. The zygote divides by mitosis on its way down the oviduct, becoming a hollow ball of cells: the blastocyst.
  2. Cortical granules release enzymes that harden the zona pellucida, so no other sperm get through.
  3. The sperm's membrane fuses with the egg's membrane.
  4. Enzymes released from the acrosome digest a path through the zona pellucida.
  5. About a week after fertilization, the blastocyst implants in the endometrium.

The cortical reaction prevents : fertilization of one egg by more than one sperm.

D3.1 examA longitudinal section of a bean seed

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D3.1Reproduction

D3.1.18The placentaHL

Finger-like give the placenta a large surface area. Across it, oxygen and nutrients pass from the mother's blood to the foetus, and and urea pass back, though the two bloods do not . With a placenta, the foetus can stay in the to a later stage of development than in mammals without one.

D3.1.20HRT and heart diseaseHL

Early studies found less coronary heart disease in women taking hormone replacement therapy, and took this as cause and effect. But it was only a : women on HRT tended to have a higher , which itself lowers the risk. Later, controlled trials showed that HRT slightly the risk.

D3.1 examHalf of an insect-pollinated flower

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D3.1.13, D3.1.17, D3.1.19Hormones of puberty and pregnancyHL

HormoneSecreted byRole
GnRHits rise in late childhood boosts LH and FSH, so sex hormones bring on puberty
hCGthe keeps the corpus luteum secreting
Progesteronecorpus luteum, then the keeps the uterus lining, so the pregnancy continues
Oxytocinpituitary glandrises once progesterone falls; contractions cause more release: feedback

A pregnancy test detects hCG in urine with that bind to it.

Word bank anthercarbon dioxidecorrelationcotyledondifferentiationembryofourhypothalamusincreasesmitosismixmonoclonal antibodiesnectaryoneovaryplacentaplumulepolyspermypositiveradiclerandomizedsocioeconomic statusstigmatestaunequallyuterusvilli

Answer key

Every box on the sheet with its gaps filled in, as the subtopic reads in full.

  1. TableAsexual or sexual?

    AsexualSexual
    Gametesnonemade by meiosis, then fused at fertilization
    Offspringgenetically identical to the parentnew combinations of alleles
    Best when the environment isstable, and the parent already well adapted to itchanging, as variation lets some offspring adapt

    The male gamete travels to the female gamete, so it is much smaller, with fewer food reserves, and is made in far greater numbers.

  2. LabelThe male system

    1. testis
    2. epididymis
    3. sperm duct
    4. seminal vesicle
    5. prostate gland

    Sperm and the fluid added to them leave together as semen, through the urethra. The fluid holds sugar for the sperm to respire and is alkaline, protecting sperm from the acid of the vagina.

  3. LabelThe female system

    1. ovary
    2. oviduct
    3. endometrium
    4. cervix
    5. vagina

    About once a month an egg is released from a follicle: ovulation. If it is fertilized, the embryo develops in the uterus, whose muscular wall contracts to push the baby out at birth.

  4. LabelOne cycle, four hormones

    1. FSH
    2. LH
    3. oestradiol
    4. progesterone
    5. ovulation

    Late in the first half, a high level of an ovarian hormone triggers a surge of the pituitary hormones by positive feedback. After the egg is released, the empty follicle becomes the corpus luteum, and its hormones hold the pituitary hormones down by negative feedback. IVF suspends this natural cycle, then high hormone doses cause superovulation.

  5. OrderFertilization in humans

    1. The sperm's cell membrane fuses with the egg's cell membrane.
    2. The sperm nucleus enters the egg; the sperm's tail and mitochondria are destroyed.
    3. The membranes round the sperm and egg nuclei break down.
    4. The condensed chromosomes from both gametes gather on one spindle.
    5. A joint mitosis produces two diploid nuclei: the embryo has two cells.

    Each gamete brings one haploid set of 23 chromosomes.

  6. LabelBuilt for insects

    1. petal
    2. nectary
    3. anther
    4. stigma
    5. ovary

    Animals or wind carry pollen between plants. Plants promote cross-pollination: male and female parts ripen at different times, or sit in separate flowers or on separate plants, and in many species genetic self-incompatibility stops a plant fertilizing itself. Self-pollination would mean inbreeding, which lowers genetic diversity and vigour.

  7. OrderFrom pollen to seedling

    1. An insect carries pollen to the stigma of a flower on another plant.
    2. A tube grows from the pollen grain down the style to an ovule.
    3. A male gamete from the tube fuses with the female gamete in the ovule.
    4. The zygote grows into an embryo, and the ovule becomes a seed.
    5. Animals, wind or water carry the seed away from the parent plant.
    6. The seed absorbs water, stored food is mobilized, and the embryo grows into a seedling.

    Carrying pollen is pollination; carrying seeds away from the parent, which cuts competition, is dispersal.

  8. TableHormones of puberty and pregnancy HL

    HormoneSecreted byRole
    GnRHhypothalamusits rise in late childhood boosts LH and FSH, so sex hormones bring on puberty
    hCGthe embryokeeps the corpus luteum secreting
    Progesteronecorpus luteum, then the placentakeeps the uterus lining, so the pregnancy continues
    Oxytocinpituitary glandrises once progesterone falls; contractions cause more release: positive feedback

    A pregnancy test detects hCG in urine with monoclonal antibodies that bind to it.

  9. TableMaking sperm and eggs HL

    SpermatogenesisOogenesis
    Gametes per meiosisfourone, plus small polar bodies
    Cytoplasmshared equally; most is lost as the sperm formshared unequally, so the egg keeps nearly all of it
    Gametes releasedhuge numbers, continually from pubertyusually one a month, from puberty to menopause

    Both begin with mitosis, then cell growth, the two divisions of meiosis and finally differentiation.

  10. OrderFertilization to implantation HL

    1. Enzymes released from the acrosome digest a path through the zona pellucida.
    2. The sperm's membrane fuses with the egg's membrane.
    3. Cortical granules release enzymes that harden the zona pellucida, so no other sperm get through.
    4. The zygote divides by mitosis on its way down the oviduct, becoming a hollow ball of cells: the blastocyst.
    5. About a week after fertilization, the blastocyst implants in the endometrium.

    The cortical reaction prevents polyspermy: fertilization of one egg by more than one sperm.

  11. GapsThe placenta HL

    Finger-like villi give the placenta a large surface area. Across it, oxygen and nutrients pass from the mother's blood to the foetus, and carbon dioxide and urea pass back, though the two bloods do not mix. With a placenta, the foetus can stay in the uterus to a later stage of development than in mammals without one.

  12. GapsHRT and heart disease HL

    Early studies found less coronary heart disease in women taking hormone replacement therapy, and took this as cause and effect. But it was only a correlation: women on HRT tended to have a higher socioeconomic status, which itself lowers the risk. Later, randomized controlled trials showed that HRT slightly increases the risk.

  13. Exam diagramHalf of an insect-pollinated flower

    1. anther
    2. stigma
    3. ovary
    4. nectary

  14. Exam diagramA longitudinal section of a bean seed

    1. testa
    2. cotyledon
    3. plumule
    4. radicle