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Biology IGCSE > Chapter 16 > Flashcards

Chapter 16 Flashcards

Reproduction

1
Q

What is reproduction?

A

It is the process of producing more of the same organisms.

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2
Q

What is Asexual reproduction?

A

It is a process resulting in production of genetically identical offspring from one parent.

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3
Q

What are the Advantages of Asexual reproduction?

A
  • Faster reproduction- no mate needed.
  • Consistent offspring- all good characteristics are passed onto offspring.
  • No pollination
  • Plants store large amounts of food for rapid growth.
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4
Q

What are the Disadvantages of Asexual reproduction?

A
  • No genetic diversity
  • Vulnerable to disease- if one parent has no resistance, all offspring will suffer.
  • Lack of dispersal leads to competition of resources.
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5
Q

What is Sexual Reproduction?

A

It is a process that involves the fusion of 2 gametes to form a Zygote.
- It is production of offspring that are genetically different from each other.

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6
Q

What is Fertilisation?

A

It is the fusion of the nuclei of gametes/sex cells.
- Sperm/ ovum
- pollen grain/ovum

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7
Q

What are the advantages of Sexual reproduction?

A

There is increased genetic diversity and variation
- Less vulnerable to disease
- Reduced competition as seeds are dispersed away from the parent.

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8
Q

What are the Disadvantages of Sexual reproduction?

A
  • 2 parents are needed
  • Growth of new plants is slow.
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9
Q

What are the parts and functions of a flower?

A
  • Sepal: Protects unopened flower.
  • Petals: Brightly colored/scented to attract insects.
  • Anther: Contains 4 pollen sacs where pollen grains are produced (sex cells)
  • Filament: Stalk that supports Anther.
  • Stigma: Sticky surfaces catches pollen
  • Style: Connects Stigma -> Ovary
  • Ovary: produces Ovum (Sex cell)
  • Ovule: Found INSIDE Ovary, it contains female sex cells.
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10
Q

What are Stamens?

A

These are Male reproductive organs that consist of Anther and Filament.

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11
Q

What are Carpels?

A

These are Female reproductive organs that consist of Style, Stigma and ovary with ovules inside.

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12
Q

What is Pollination?

A

Pollination is the transfer of pollen grains from the Anther to Stigma.
Either by insects or wind.

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13
Q

What are the features of Insect-pollinated flowers?

A
  • Petals are brightly colored/scented to attract insects.
  • Pollen is produced in small amounts.
  • Pollen grains are round, sticky, large and spiky to attach to insect bodies.
  • The produce Nectar.
  • Stigma is Sticky for grains to attach.
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14
Q

What are the features of wind-pollinated flowers?

A
  • Petals are small and dull
  • Pollen is smooth and light to be easily carried by wind.
  • Pollen is produced in Large amounts since theres low chance of reaching another flower.
  • No nectar
  • Stigma is feathery outside the flower to increase S.A to catch pollen grains.
  • Anther swings loosely outside flower to release pollen grains easily when wind blows.
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15
Q

What is Self-Pollination?

A

It is the transfer of pollen grains from Anther to Stigma of the same flower OR different flower of the same plant.

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16
Q

What is Cross-pollination?

A

It is the transfer of pollen grains from Anther to Stigma of a flower on a DIFFERENT PLANT of the same species.

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17
Q

What are the differences between self and cross pollination?

A
  • In SELF; No genetic variation occurs.
    -It limits offspring from changing in environmental conditions.
  • In SELF; It can take place without pollinators, this prevents extinction.
  • In CROSS; There is genetic variation, giving offspring chance to adapt to environment changes
  • In CROSS; It depends on pollinators.
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18
Q

What is Fertilisation? (plants)

A

This is when a pollen nucleus fuses with a nucleus in an ovule.

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19
Q

What are the steps of fertilisation in Plants?

A

1) A pollen grain lands on the Stigma.
2) A microscopic pollen tube grows out of the grain, down the Style and into the Ovary through the micropyle (a small hole to the ovule).
3) Pollen nucleus moves down the pollen tube into the Ovule.
4) The Pollen nucleus fuses with the Ovum nucleus.
5) A seed is developed.
5) Ovary wall becomes a fruit.

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20
Q

What is Germination and its factors?

A

It is the beginning of seed growth.
3 essential factors:
- Water: Causes seed to expand and activates enzymes to initiate growth.
- Oxygen: For respiration to release energy for growth.
- Temperature: Increases the rate of germination as enzyme-catalyzed reactions are dependent.

21
Q

What is fertilisation? (humans)

A

It is the fusion of the male and female gamete nuclei to form a zygote -> embryo.
- Takes place in Oviducts.

22
Q

What are the parts of the Male reproductive system?

A

Testes, Scrotum, Sperm duct, Prostate gland, Urethra, and Penis.

23
Q

What are the parts of the Female reproductive system?

A

Ovary, Oviducts, Uterus, Cervix, and Vagina.

24
Q

What are the adaptive features of Sperm?

A
  • They have a Flagellum to swim towards egg cell.
  • Packed with mitochondria for energy for movement.
  • Acrosome releases enzymes to break down the egg cell protective layer.
25
What are the adaptive features of Egg cells?
- Cytoplasm contains energy stores to support development of fertilisation. - Jelly coat changes after fertilisation to prevent multiple sperm entering the egg.
26
What is the process of Ovulation?
As an egg/ovum matures, cells around it divide and produce a fluid-filled sac called a Follicle. - Once matured, the Follicle bursts and releases the Ovum with a coating of its cells. - The Ovum is moved down the oviduct by action of Cilia. - If the ovum meets sperm cells in the oviduct, it may be fertilised. *The released Ovum is enclosed in a jelly-like coat called the Zona Pellucida which sperm have to get through.
27
What is Ovulation? (short)
It is the release of a matured Ovum from its follicle down the Oviduct.
28
What is Implantation?
Implantation is when in the early stage of development, the Zygote divides by Mitosis to form an embryo (a ball of identical cells) and sinks down into the lining of the Uterus.
29
What is the Placenta?
The Placenta is a disc-like structure formed from some cells of the embryo. - It develops during pregnancy and attaches to the uterine wall. - It acts as interface between the mothers blood supply and the developing fetus. > In this way, the high pressure of the mothers blood wont damage delicate vessels of the Embryo. - The blood vessels of placenta and uterus are close so oxygen, amino acids, glucose and salts can pass from mother -> embryo.
30
What is the role of the Placenta?
Placenta provides oxygen and nutrients to the fetus. - It removes waste products from the fetus. - This is done by Diffusion. - Placenta produces hormones that help maintain pregnancy (Oestrogen and Progesterone) - It allows substances to diffuse into embryos blood - However, it cannot prevent some toxins/pathogens.
31
What is the Umbilical cord?
It is a tube that connects the Fetus to the Placenta. - It provides the fetus with nutrients and oxygen from the mothers blood through the Placenta. - It also removes waste products.
32
What is the Amniotic sac?
Amnion is a fluid-filled sac that encloses the embryo in the Uterus. - It surrounds and protects the Fetus. - It contains Amniotic fluid. - It helps regulate temperatures around the Fetus. - Prevents unequal pressure acting on the Embryo.
33
What is Amniotic fluid?
It is the fluid of the Amniotic sac. - It cushions and protects the developing Fetus. - It helps the fetus move and develop properly. - It helps regulate temperatures of the Fetus.
34
What are the Sexual Hormones for Puberty?
Testosterone and Oestrogen.
35
What is the affect of Testosterone in males?
It develops the secondary sexual characteristics: - Growth of the Penis and Testes - Growth of facial/body hair - Muscles develop - Voice deepens - Testes produce sperm
36
What is the affect of Oestrogen in Females?
It develops the secondary sexual characteristics: - Growth of Breasts - Widening of hips - Body hair grows - Menstrual cycle begins - Size of Uterus and Vagina increase
37
What are the steps of the Menstrual cycle?
- The ovaries release an ovum every 28 days. - The uterus lining thickens in preparation for embryo implantation. - If the Ovum is not fertilised, the uterus lining breaks down. - The unfertilised egg and lining pass out of the cervix and vagina.
38
What are the changes of ovaries in the menstrual cycle?
Follicle -> matures -> Ovulation. - Follicle releases an egg. - Once done, the empty follicle develops into a solid body called the Corpus Luteum. - If Ovum isn't fertilised, the Corpus breaks down.
39
What hormones control the cycle and pregnancy?
FSH -> Oestrogen -> LH -> Progesterone
40
What is the role of Oestrogen?
It is produced by the ovaries during the menstrual cycle and by the Placenta during pregnancy: - It Stimulates growth of the uterus lining, making it thicker for embryo implantation. - It causes the follicle which contains the Ovum to mature. - Stimulates LH production. - DECREASES FSH production.
41
What is the role of Progesterone?
It is produced by the ovaries during the menstrual cycle and by the Placenta during pregnancy: - Helps maintain the thick uterus lining during the cycle and pregnancy. - DECREASES FSH production. - If egg is NOT fertilised, the Progesterone level drops causing the uterine lining to break down.
42
What is the role of FSH?
It is Follicle stimulating hormone. - It is produced by the pituitary gland. - It causes a single follicle with an egg to develop and mature. - It stimulates the Ovaries to release Oestrogen.
43
What is the role of LH?
It is Luteinising hormone. - It is produced by the Pituitary gland, which is stimulated by Oestrogen. - It stimulates Ovulation for an egg to release. - It stimulates Progesterone production. (corpus luteum produces progesterone)
44
What is STI?
It is a sexually transmitted infection through sexual contact.
45
What does HIV stand for?
IT is Human Immunodeficiency Virus which is a pathogen causes STI. - It is present in bodily fluids of infected people. (Blood and Semen)
46
What does HIV do?
HIV attacks and weakens the body's immune system by reducing the number of functioning lymphocytes, and ability to produce antibodies leaving the body vulnerable to infections and disease.
47
What is AIDS?
HIV may leads to AIDS. It makes an individual highly vulnerable to other pathogens as their wbc's are unable to fight infection. - This may result in death.
48
What are methods of HIV transmission?
- Unprotected sex - Sharing needles - Blood transfusions - From mother to fetus through placenta or breastfeeding.
49
How are STIs controlled?
- Limiting sexual partners - Using condoms - Getting tested - Raising awareness - Abstinence from sex - Sterilized needles

Biology IGCSE (19 decks)

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