Topic 3 - Plant and Human Reproduction Flashcards
(34 cards)
What are 4 differences between asexual and sexual reproduction?
- Sexual requires 2 parents, asexual requires only 1
- Sexual requires gametes, asexual does not
- Sexual occurs through the fusion/fertilisation to produce a zygote, asexual can occur through binary fission (bacteria) or budding (yeast and some plants)
- Sexual produces genetically varied offspring, asexual produces genetically identical offspring.
- What is the definition of sexual reproduction?
- What is the definition of asexual reproduction?
- Sexual reproduction is the formation of varied offspring from the fusion of two gametes (from two parents)
- Asexual reproduction is the formation of identical offspring without the fusion of gametes, only involving one parent
- What is 1 advantage and 2 disadvantages of sexual reproduction
- What are 2 advantages and 1 disadvantage of asexual reproduction
SEXUAL:
✔️ 1. Genetic Variation - Offspring can adapt and evolve (increased chance of survival)
❌ 1. Slower than asexual (more stages involved)
❌ 2. Time and energy is used up competing for a mate
Asexual:
✔️ 1. Genetically Identical offspring - Good when parent is well adapted
✔️ 2. Quick - Bacteria can produce offspring in 20 mins
❌ 1. All faulty genetic material is passed on
What are three natural methods of asexual reproduction?
- Runners e.g. Strawberries (Horizontal stems)
- Tubers e.g. Potatoes (Fleshy underground storages)
- Bulbs e.g. Onions (Bases of leaves swollen –> Foods(
What is one artificial method of asexual reproduction?
Cuttings e.g. Spider Plants (Cut off part of leaf)
Can you label plant sexual organs?
PETALS - Bright colourful leaves around edge
FILAMENT - Thin line holding up anther, sprouting from centre of flower
ANTHER - Sits on top of filament
STIGMA - Sits on top of style
STYLE - Holds up stigma
OVARY - At top of stem
STEM - Holds up whole flower
What is the definition of pollination? What is it usually carried out by?
The transfer of pollen grains (male gamete) from anther to stigma where the ova (female gamete) is held to allow gametes to fuse (fertilisation)
Pollination is usually carried out by wind or insects.
- What is the name for the male reproductive system as a whole in plants (Anther + Filament)
- What is the name for the female reproductive system as a whole in plants (Stigma + Style + Ovary)
- Stamen
- Carpel/Pistil
What are the functions of the:
1. Sepals
2. Petals
3. Stamens
4. Anthers
5. Stigma
6. Ovary
7. Nectary
8. Style
9. Filament
- To protect the unopened flower bud
- May be brightly coloured to attract insects
- The male part of the flower
- To produce male gametes (in pollen grains)
- To collect pollen grains
- To produce the female gametes (in ovules)
- To produce sugary nectar to attract insects
- Holds up stigma
- Holds up anther
What are the differences in wind vs insect pollinated plants in:
1. Position of Stamen
2. Position of Stigma
3. Type of Stigma
4. Size of Petals
5. Colour of Petals
6. Nectaries
7. Pollen grains
WIND:
Stamen hangs outside plant
Stigma hangs outside flower
Stigma is feathery (to catch drifting pollen)
Small petals
Dull petals
No nectaries
Huge number of pollen grains, smooth and light (so easily carried by wind)
INSECT:
Stamen is inside flower
Stigma is inside flower
Stigma is sticky
Large petals to attract insects
Colourful petals to attract insects
Nectaries to produce scent to attract insects
Moderate number of sticky, spiky pollen grains
What is the process between when the pollen grain lands on the stigma and the egg is fertilised?
- A Pollen Tube grows down the style. There are two sperm ‘nuclei’ in each pollen grain
- The pollen tube enters the ovary via a small hole called the ‘micropyle’
- ONE pollen grain fuses with the egg, producing a zygote
- The fertilised ovule becomes the seed, the ovule wall becomes the seed coat (testa)
- The ovary grows and becomes a fruit
- The OTHER/SECOND male gamete attaches to two cells in the embryo sac, forming an endosperm, this provides a starchy food for the seed to grow before it begins to germinate.
What is the definition of fertilisation?
A male gamete nuclei fuses with the femal gamete nuclei, producing a zygote.
3 marker:
Fusion (1)
Male + Female gamete (1)
Produces Zygote (1)
What is self-pollination?
When a plant pollinates itself, it’s own pollen goes into it’s own stigma
What are the 3 main parts of a seed?
- The zygote develops into an Embryonic Plant (Embryo) with a small root (radicle) and shoot (plumule) and one or two seed leaves called cotyledons
- Food store- Starch for the plant to use until it can carry out photosynthesis
- Seed coat - A touch protective outer covering
What is it called when a seed has one seed leaf? How about two seed leaves?
One seed leaf - Monocot
Two seed leaves - Dicot
What is germination?
The growth of a new plant from a seed
- Why does a seed not germinate as soon as it is released form the parent plant?
- When will it begin to germinate?
- When it is first released form a plant, it is very dry. The low water content restricts a seed’s metabolism so it can survive but remains dormant
- Dormancy ends when a seed germinates, because the seed’s food store is broken down by enzymes, and it can respire aerobically (under certain conditions)
What are the three factors that influence a seeds dormancy (the WOW factors)?
W - Water - Lets the seed swell and the embryo starts to grow
O - Oxygen - Needed for aerobic respiration
W - Warmth - Increases growth rate and enzyme activity (But very high temperatures will denature the enzymes)
What will the radicle do? What will the plumule do?
Radicle: Grows down into soil where it will absorb water and mineral ions
Plumule: Grows up towards light, so it can begin photosynthesis
What are gametes?
An organisms sex cells
What is the process of fertilised egg –> Foetus
- The fertilised egg will develop into a ball of cells (Zygote)
- The zygote divides (by mitosis) into an embryo
- Ultimately, the mitosis forms a foetus from the embryo
- What are embryonic stem cells?
- What are adult stem cells (bone marrow)?
- Embryonic stem cells are undifferentiated cells that can specialise into any type of cell (e.g. Muscle, Nerve, Tissues or Organs)
- Adult stem cells are cells that can only turn into blood cells
- What is internal fertilisation?
- What is external fertilisation?
- Internal fertilisation is the fusion of an egg and sperm cell (nuclei) during sexual reproduction INSIDE the female body (producing a zygote) - E.g. Humans
- External fertilisation is when a male organism’s sperm fertilises a female organism’s egg OUTSIDE the female’s body. E.g. (Most) Fish, and Amphibians
What are the three steps of fertilisation in humans?
- The egg is released into the oviduct/fallopian tubes from the ovary
- Sperm is ejaculated into the vagina and travels up the cervix
- The egg and sperm meet at the oviduct and the process of fertilisation begins
