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Gymnastics and tumbling > Chapter 22 (Plant Reproduction) > Flashcards

Chapter 22 (Plant Reproduction) Flashcards

1
Q

Definition of pollination

A

The transfer of pollen grains (male gamete, n) from the anther (male reproductive structures) to stigma (female reproductive structures) of another plant prior to fertilisation

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2
Q

Where are male and female gametes located

A

Male gametes - located within pollen grain
Female gametes - ovules located in ovary

for male: stamen = anthers and filaments

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3
Q

Pollinating agents.

A

Abiotic - wind, water.

Biotic - insects, other animals eg birds, bats, slugs, cats (attached to fur and in faeces)

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4
Q

Megasporanium info and microsporangium?

A

hhgiushgijsghshisdfh

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5
Q

Types of pollination?

A

Cross pollination and self pollination.

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6
Q

Advantages of self pollination?

A
  • Only 1 parent required
  • Offspring inherits alleles from parents (which have proven success) - increases inheritance of beneficial alleles.
  • Pollination not dependent on external factors for pollination, eg wind, insects.
  • As anther and stigmas are arranged in close proximity, it increases chances of SP being successful.
  • Less pollen wasted, so less energy wasted as less pollen needs to be produced.
  • Less energy used in producing features which attracts insects, eg coloured, large flowers, nectar.
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7
Q

Disadvantages of self pollination?

A
  • reduced gene pool
  • Reduced variety in population
  • reduced resistance in population
  • Evolution of new varieties less likely - evolutionary dead end.
  • Weaker alleles remain in population - weaker plants not lost/removed.
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8
Q

Advantages of cross pollination?

A
  • Increases variation in population for natural selection.
  • Ensures outbreeding occurs.
  • Wides gene pool due to mixing of alleles.
  • Increases number of heterozygotes, so less homozygous recessive or less disease genes expressed.
  • so increases allele frequency of advantageous gene
  • increases passage of favourable alleles to next generation.
  • makes them less susceptible to disease and increases survival of the species as it ensures individuals of a species can adapt better in a harsh environment if environment changes.
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9
Q

Disadvantages of cross pollination?

A
  • 2 parents required
  • Needs another plant in nearby area (not good if plants are widely scattered or rare)
  • dependant on external pollination agent eg, wind, insect.
  • More energy used to produce greater quantity of pollen and make flowers attractive to insects.
  • Lower rates of successful pollination due to distance/dependancy on insects.
  • May lose advantageous phenotype
  • Can lead to disease transmission.
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10
Q

Mechanisms for increasing insect pollination success?

A

Colourful flowers to attract insects
Food rewards (nectar or pollen) to attract insects, eg, pea plants (legumes)
Scents to attract insects
Labellum - type of petal - landing platform.
Pheremones produced
Physical adaptations - Flower mimicry eg, bee orchid, hammer orchid, pseudocopulation
chemical mimicry
Entrapment
sugars produced in nectary

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11
Q

How is pollination of flowers by insects a mutualistic relationship?

A

Insect. - gains energy from nectar or pollen it consumes

Plant. - gains gamete dispersal mechanism

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12
Q

Mechanisms for increasing wind pollination success?

A

Petals - small and green as no need to attract insects.
pollen grains - small and light + occur in large numbers. - to be carried.
Anthers exposed to wind so pollen easily blown away.
Stigma feathery + large SA to catch pollen grains landing on them
No scent or nectary.

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13
Q

Importance of the process of fertilisation

A

Fertilisation restores chromosome number to the diploid state
Fertilisation increases genetic variation

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14
Q

Two types of seeds

A

Monocotyledons

Dicotyledons

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15
Q

Differences between the two types of seeds?

A

Monocot - one cotyledon, fibrous roots, scarred vascular, parallels veins in leaf, flower petals of multiples of 3.

Dicot - two cotyledons, tap roots, ringed vascular, net-like veins in leaf, flower petals of 4 or 5.

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16
Q

endospermic seed parts?

A

Embryo
Endosperm
Testa.

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17
Q

The importance of seed dehydrating

A
  1. Decreases metabolic rate of cells within the seed
  2. Conserves energy stores in cotyledons
  3. Increases duration that seed remains viable
  4. Enable seed to be classified as ‘dormant’ and exist until favourable conditions occur for germination
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18
Q

Definition of germination?

A

The process by which a seed emerges from a period of dormancy and begins to sprout. it involves the growth and development of the embryo root and embryo shoot.

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19
Q

What are gibberellins?

A

Plant ‘hormones’ essential for germination
Act as cell signalling molecules.

Hormones - plant growth regulators.

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20
Q

Graph of dry mass vs days explained.

A

LOOK UP GRAPH AND EXPLAIN IT!!!

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21
Q

Definition of dormancy?

A

A state in which seeds are prevented from germinating even when under environmental conditions normally favourable for germination.

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22
Q

Advantages of seed dormancy?

A
  • Prevent germination during short periods of favourable conditions.
  • Ensure germination occurs when conditions are favourable for a sustained period.
  • Allows seeds to survive in unfavourable conditions.
  • Allows more time for seed dispersal
  • Prevents germination before dispersal.
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23
Q

Vernalisation definition

A

The process of inducing flowering by prolonged exposure to cold temperatures. (5 - 10 degrees C)
This switches on genes that control flowering, and promotes the transcription of those genes that produce proteins involved in flowering.

24
Q

If no vernalisation occurs?

A

Genes that control flowering aren’t switched on.
No transcription of genes to produce flowers occurs - no translation as no mRNA.
No flowers formed
No seeds produced.

25
Q

Advantages of vernalisation?

A

Induces flowering
Ensures reproductive development + seed development occurs in spring + autumn, not winter.
Coincides seed production with favourable environmental conditions of spring.
Which increases survival rates of individual plants so they can build up energy reserves.

  • Scientists can carry out vernalisation deliberately to force early flowering and seed production to produce fruit crops out of season.
26
Q

Definition of photoperiodism?

A

Response of the plant to the relative lengths of light and darkness. Triggered by periods of darkness.

27
Q

Types of plants?

A

Long -day plants
Short - day plants
Day - neutral plants

28
Q

Long day plants information

A

Day length more than 12 hours.
(short night)

Long-day plants flower when night length falls below critical photoperiod.

Eg, spinach, lettuce, radish, sugar beet, potato.

29
Q

Short day plants information?

A

Day length less than 12 hours
(Long night)

Short-day plants flower when the night lengths exceed their critical photoperiod.

Eg, rice, soya bean, onion

30
Q

Day-neutral plants

A

Day length immaterial for flowering

Flower irrespective of day length/darkness. - longer flowering season, generate fruit + food product so dec. food insecurity.

Eg, cucumber, corn, tomato, pea.

31
Q

Two types of phytochrome

A

Phytochrome exists in 2 different forms (isomers)

Pr - inactive + stable
Pfr - active + less stable

Pr conformation absorbs red light which converts it to Pfr.

Pfr conformation absorbs far red light which converts it to Pr.
Active form will gradually revert to inactive form in absence of light - photoreversible.

32
Q

Triggers for flowering

A

Temperature can trigger transformation of a leaf-producing shoot to a flower-producing shoot.

Duration of dark period.

33
Q

Sunlight and moonlight

A

Sunlight contains more red light than moonlight, so the active form is predominant during the day.

Pfr accumulates during daylight when plants are exposed to red light (as red light converts Pr to Pfr)

Pfr is converted slowly back to Pr during dark period as moonlight contains more far-red light.

At the end of the night only Pr remains, so the conversion rate between Pr and Pfr enables plant to measure day length.

The proportions, ie, ratio of Pr to Pfr determine when flowering occurs

34
Q

Analogy to remember photoperiodism?

A 
SID the LAD.
Short day plants 
Pfr inhibits flowering
Pfr levels must be low to flower 
(must exceed a critical night length)

Long Day plants
Pfr Activates flowering
Pfr levels must be high to flower
(night must be less than critical length)

35
Q

Risks/disadvantages of GM crops?

A

Reduce biodiversity
No available info about how GM crops affect human health.
Modified plants may outcompete wild type plants
inserted genes can transfer to wild plants, or enter the food chain.

36
Q

Benefits of GM crops?

A
  • Increase in primary productivity of food crops improved.
  • Could produce more food.
  • Increased photosynthesis would reduce carbon emissions and reduce greenhouse gases.
  • Upgrading wild plants would make whole ecosystem more productive.
37
Q

What are cereals?

A

Eg, wheat, rice, oats, corn, barley, maize.
Use of cereal crops is increasing as human pop is incr. So annual production has to incr. to meet demand.
On occasions, demand can be > than supply, so stock reserves are used.

38
Q

Definition of global supply?

A

Annual production of a specific crop plus the stock piles that have been carried over from previous years.

39
Q

Food security of staple foods?

A 
World pop incr. 
- Land + water availability decreasing
- fertiliser costs increasing
- Fuel costs increasing
So producing sufficient food sustainability is becoming increasingly difficult.
40
Q

Endosperm for cereals ->

A

Source of nutrients for humans

Is rich in starch (Amylose + amylopectin) so good supply of carbohydrates.

41
Q

Adaptations to ensure cross pollination occurs?

A

Structural mechanisms associated with flowers and cones
Physiological mechanisms associated with the flowers and cones

TO INCREASE:
Separate male and female plants
Separate male and female flowers (on same plant)
Timing of gamete maturation and release.

42
Q

Adaptations to reduce self-pollination?

A
  • Male and female part of the plant mature at different times of the year
  • Morphological adaptations - the physical structures of the male and female parts prevent self-pollination
  • Biochemical adaptations - chemicals on the stigma prevent pollen grain from the same flower producing a pollen tube.
43
Q

What is meristematic tissue?

A

Found in plants
Consists of undifferentiated cells capable of cell division
Can differentiate into all the other tissues and organs that occur in plants.
Continue to divide until they are differentiated and then lose the ability to divide.

44
Q

What is a hilum?

A

Point where ovules were previously attached to the wall of the ovary.

45
Q

Role of water in germination?

A

Water enters seed by osmosis

This breaks dormancy by

  1. Softening testa
  2. Mobilising food reserves (in endosperm)
  3. Hydrolyses macromolecules (oil, proteins, amylose)
  4. Acts as a solvent for biochemical reactions
  5. Activates enzymes
  6. Washes out germination and growth inhibitors.
  7. Causes cells to swell to promote cell elongation and maintains cell turgidity
  8. Cell elongation then results in testa rupturing
46
Q

What is a seed coat?

A

Outermost covering of the seed.
Formed from two integuments outside ovule.
Outer forms testa.

47
Q

Characteristics of meristematic cells?

A

Thin cell wall
Absent or small vacuole
Dense cytoplasm
Prominent nuclei.

48
Q

What is the epicotyl?

A

Region of the embryo above the stalks of the cotyledons. Growth of hate epicotyl region is responsible for extension of stem above soil surface.

49
Q

What is the hypocotyl?

A

Region of the seed present below the cotyledons and above the radicle.
Function - to push the cotyledons above the soil surface during germination

50
Q

Role of oxygen in germination?

A

Obtained by diffusion through micropyle

  1. Required for increased rate of aerobic respiration
  2. Oxidises glucose, lipids, etc…
  3. To produce MORE ATP.
  4. Increased energy release is used for cell division
  5. Resulting in growth of radicle and plumule leading to exposure of cotyledons.
51
Q

What is the radicle?

A

Embryonic root

Radicle comes out of the seed through micropyle.

52
Q

What is the cotyledon?

A

Embryonic leaf in seed. Provides nutrients and protection to embryo.

53
Q

What is the plumule?

A

Embryonic shoot with vegetative parts like leaves and stems.

54
Q

Role of pH in germination?

A
  • Affects metabolic rate
  • Optimum pH for enzymes to digest food reserves for respiration and growth.
    eg, Amylase - break ONLY alpha 1-4 glycosidic bonds to release maltose molecules.
    Eg, Maltase - break alpha 1-4 glycoside bonds to release alpha glucose.
55
Q

Role of temperature in germination?

A
  • Increases metabolic rate
  • optimum temp for enzymes to digest food reserves for respiration and growth.
    eg, hydrolyse amylose to maltose (amylase)
    hydrolyse maltose to alpha glucose (maltase)

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