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Biology Mod 5 Heredity > Mod 5 Heredity > Flashcards

Mod 5 Heredity Flashcards

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1
Q

What is sexual reproduction?

A

Fusion of two gametes to form a zygote

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2
Q

What are the advantages of sexual reproduction?

A
  • Fertilisation is less risky and young are more likely to survive
  • Unfavourable genetic variations can be eliminated from the population
  • Creates genetic variation which can increase adaptations
  • Populations are better suited to adapting to environmental changes
  • Improves long term evolutionary potential of populations
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3
Q

What are the disadvantages of sexual reproduction?

A
  • Requires more energy
  • Makes organisms more vulnerable to predators
  • Fewer offpsring produced
  • Slower reproductive rate - fewer organisms are produced over a longer period of time
  • Potential for sexually transmitted diseases throughout the population
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4
Q

Describe the process of fertilisation

The meeting of two gametes

A

Each species has a certain number of chromosomes arranged in homologous pairs within their body (humans have 46 & 23 pairs)
Diploid is when cells have 46 chromomes and is used to describe somatic cells
Haploid is when they only have 23 chromosomes and are used for gametes
When two gametes meet, the zygote becomes diploid

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5
Q

What are hormones?

A

Chemical substances that act as messengers within the body, co-ordinating functions

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6
Q

What are sex hormones?

A

Hormones that affect the growth or functioning of reproductive organs or the development of secondary sex characteristics

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7
Q

What is the role of the pituitary gland?

A

Secrete stimulate or inhibit other endocrine glands, regulating the release of their hormones for growth, metabolism and reproduction

Growth, metabolism and reproduction

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8
Q

What is the main hormone in Spermatogenesis?

And additional hormones?

A

Testosterone but LH, FSH and oestrogen are also present in low amounts

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9
Q

What is spermatogenesis?

A

Developement of sperm cells within the male reproductive system

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10
Q

What parts of the body does spermatogenesis involve?

A

Hypthalamus, Leydig Cells and Sertoli Cells in the testes & Pituitary Gland

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11
Q

What is the role of the Hypothalamus in Spermatogenesis?

A

Produces GnRH which initiates pituitary gland to produce LH and FSH which stimulates Sertoli Cells to facilitate sperm production

GnRH -> Pituitary -> LH & FSH -> Sertoli Cells -> Sperm

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12
Q

What is the role of Sertoli Cells in Spermatogenesis?

A

Facilitates sperm production and produces inhibin once the sperm count has been reached

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13
Q

What is the role of Inhibin in Spermatogenesis?

A

Protein secreted by Sertoli Cells to the Pituitary Gland to decrease the production of FSH only

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14
Q

What is the role of Leydig Cells in Spermatogenesis?

A

Decrease the levels of testosterone which helps the pituitary gland stop producing LH and FSH

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15
Q

Explain the structure of sperm

A

Consists of head, neck, tail and middle piece & acrosome

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16
Q

Explain the role of the acrosome in reproduction

A

Acrosome contains digestive enzymes that break down the zona pellucida and assist in sperm penetration

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17
Q

plain

What is the role of the middle piece of the sperm?

A

Contains mitochondria which helps with movement

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18
Q

Explain the follicular phase

Day 1-14

A
  1. FH starts maturation of follicle
  2. Cells lining follicle secrete oestrogen which promotes production of LH
  3. Oestrogen peaks at Day 12 which causes peak in LH which triggers ovulation
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19
Q

What is the role of the fimbriae?

A

Small finger like projections on the outside of the ovaries that assist in moving the ovum to the fallopian tubes

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20
Q

Explain the luteal phase

Day 15-28

A
  1. LH causes corpus lutem (burst follicle) to build up lutein which turns it yellow
  2. Corpus luteum secretes progesterone which thickens endometrium for ovum to attach to
  3. Corpus luteum breaks down once placenta has formed or fertilisation does not occur
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21
Q

How does the corpus luteum know if fertilisation has occured?

A

Upon fertilisation, the hormone called HcG is released which signals that fertilisation has been successful and the corpus luteum produces progesterone for three months until the placenta takes over

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22
Q

What happens to the corpus luteum if implantation does not occur?

A

The corpus luteum degrades once the chemical trigger from the HCG is absent. The corpus luteum decreases the production of progesterone. The decrease in progesterone signals to the reproductive system that implantation was not successful and endometrial lining and egg sheds

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23
Q

What is the role of progesterone?

A

Thickens the endometrium and stimulates glands in the endometrium to release nutrients for the early embryo

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24
Q

What is the role of oestrogen?

A
  • Helps an ovum mature and burst from it’s follicle during ovulation
  • Maintains thickness of endometrium
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25
Q

What is the role of LH in the ovarian cycle?

A

Rises quickly which triggers ovulation to occur

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26
Q

What is the role of FSH in the Ovarian Cycle?

A

Starts the maturation of a follicle

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27
Q

What is the role of progesterone during pregnancy and birth?

A
  • Stimulates secretion of mucus by the cells lining the endometrium
  • Suppresses uterine activity
  • Reduces mothers response to foecal antigens
  • Prevents lactation during pregnancy
  • Strenghthens muscles of pelvic walls to prepare for labour
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28
Q

How long after a failed implantation does it take for the corpus luteum to degrade & what is the name of the new cell?

A

8-10 days after ovulation, forms the corpus albicans

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29
Q

Viviparous

A

Fertilised egg develops within the mother’s body and is born fully alive

30
Q

What type of organisms generally use asexual reproduction?

A

Simple

31
Q

What type of organisms generally use sexual reproduction?

A

Complex

32
Q

What type of reproduction is mitosis

Add a brief description on waht mitosis is

A

Asexual identical cell replication

Seen in worms & single celled yeast organisms

33
Q

What is budding and is it sexual or asexual?

A

Asexual - New organism is developed from a small part of the parent’s body

Hydra and yeast

34
Q

What is parthenogenesis and is it sexual or asexual?

A

Asexual - Embryo develops directly from egg without fertilisation and young are produced as genetic clones of their mother

Bees and wasps

35
Q

What is fragmentation and is it sexual or asexual?

A

Asexual - In multicellular organisms, the body of the organism breaks into two or more parts which regernates the missing pieces to form a complete individual

Marine worms

36
Q

Fertilisation

A

Sexual - when a sperm fuses with a ovum to create a zygote

37
Q

What is asexual reproduction?

A

One parent produces offspring with genetic makeup that is identical to the parent

38
Q

What are the advantages of asexual reproduction?

A
  • Efficient form of reproduction
  • Less time and energy required to produce the offspring
  • Population sizes can rapidly increase in correct environments
  • No need for sexual partner
  • Offspring are identical to their mother so they’re genetically suited to their environment
39
Q

What are the disadvantages of asexual reproduction?

A
  • Rapid population growth can lead to overcrowding and competition for resources
  • Lack of genetic variation can cause death of the entire population if a disease or pathogen enters the environment
40
Q

What are hermaphrodites and what are the advanatges and disadvantages of hermaphroditism?

A

Advantages: Beneficial in oragnisms with low populatinod densities where finding a mate is difficult
Disadvantages: Low genetic variation and more energy required for organism to grow two sets of reproductive systems

41
Q

What is internal fertilisation?

A

When the Gamete is deposited inside the moist reproductive tract of the female

42
Q

What are the advantages of internal fertilisation?

A
  • Fewer gametes are required for sufficient number of offspring
  • More control of mate choice → quicker natural selection which improves overall health of population over time
  • Organisms aren’t limited to aquatic/moist environments
  • Higher chance of fertilisation
  • Organisms aren’t at risk of external environmental factors like temperature, infection and predation
43
Q

What are the disadvantages of internal fertilisation?

A
  • Requires more energy and generally produces less offspring
  • Requires mating behaviours and finding a mate
  • Generally takes longer for birth
44
Q

What is external fertilisation?

A

Both gametes are released outside of the body and fertilised in the environment

45
Q

What are the advantages of external fertilisation?

A
  • Little no parental care
  • Dispersal of gametes means little to no compeition for food and environment –> rapid population recovery
  • Low energy
46
Q

What are the disadvantages of external fertilisation?

A
  • More gametes must be produced in order to ensure some offspring survive
  • Vulnerable to predation, infection etc
  • Can’t choose which gametes to fertilise with - often won’t posses favourable traits
  • Possibility that gametes don’t meet and fertilise
47
Q

Compare internal and external fertilisation

A

Gametes:
- Internal: large number of male produced and small number of female
- External: large number of male and female gametes produced
- Similarities: both require ovum and sperm

Fusion:
- Internal: occurs in moist reproductive tract of female
- External: occurs in external environment
- Similarities: both require close proximity and wet environment to prevent dehydration of gamete

Environment for Zygote:
- Internal: develops inside mothers body until birth where temperature is controlled and there is a lower chance of zygote loss
- External: external wet environment where they are vulnerable to predation, infection etc
- Similarities: zygote needs watery environment to develop

48
Q

What is the role of the anther in plants?

A

Produces pollen

49
Q

What is the role of the filament in plants?

A

Stalk that hols up the anther

50
Q

What are the male parts of a flower called?

A

Stamen

51
Q

What is the role of the ovary in plants?

A

Where ovules are produced for fertilisation

52
Q

What is the role of the Style in plants?

A

Connects the stigma to the ovary

53
Q

What is the role of the sigma in plants?

A

Sticky surface in which pollen is collected

53
Q

What are the two types of sexual reproduction in plants?

A
  • Self Pollination
  • Cross Pollination
54
Q

Describe the process of sexual reproduction in plants

A
  1. Pollen is produced in the anther
  2. When pollen touches the stigma they become trapped to it’s sticky surface
  3. The Pollen’s Tube Cell creates a pathway for the Generative Cell to travel down the style and into the ovary
  4. The Generative Cell divides into two sperm cells which fertilise the two polar nuclei and the egg inside the ovule
  5. The fertilised polar nuclei form the endosperm which provides nutrients to the zygote & the fertilised egg becomes the zygote
  6. After fertilisation the ovule matures into a seed which contains the zygote and the endosperm and is then dispersed to germinate –> the ovary is replaced by a fruit to nourish and protect the seed and make it attractive for germinators
  7. Once the seed has germinated, the zygote develops into an embryo and a new plant forms
55
Q

What is self pollination?

A

When a plant is fertilised by its own pollen

56
Q

What are the advantages of self pollination?

A
  • Plant doesn’t need to waste energy on attracting features like flowers
  • Consistent reproduction as plants don’t need to rely on external agents like wind and insects
  • Independence from pollinators: Plants don’t require help from pollinators to reproduce and can survive in areas with little animals or if there is an event that reduces the population of pollinators
57
Q

What are the advantages of seed dispersal?

A
  • Reduces overcrowding and competition for nutrients
  • Increases continuity of species in case of an environmental threat in one area like fire/flood
58
Q

What are the disavantages of seed dispersal in plants?

A
  • Loss of seeds if they are deposited in an area not suitable for growth
  • Inability to escape deteriorating environments
  • Predation before the seed germinates
59
Q

What are the disadvantages of self-pollination?

A
  • Less immunity of the plant due to little genetic variation
  • New plant varieties cannot be created
60
Q

What is cross pollination?

A

When the pollen of one plant fertilises another plant of the same species

61
Q

What are the advantages of cross pollination?

A
  • Healthier children
  • More seeds that are successful
  • Greater genetic diversity
62
Q

What are the disadvantages of cross pollination?

A
  • More energy for attracting features like petals etc
  • Pollinators are always required and can endanger the plant in case of unavailability
  • Lots of wasted pollen as it requires a lot of pollen as they have to travel long distances and the stigma is very small
63
Q

Coral Spawning

A
  • Shed millions of gametes into the sea that are released when the coral reproductive cycle is synced –> through envrironmental indicators like temperature,tides etc
  • Gametes meet in the ocean and fertilise
  • When one coral colony starts to spawn pheromones released alongside the gametes trigger nearby coral to spawn which results in coordinated spawning over a large area

Asexual Reproduction

64
Q

The Splash Tera

A
  • Two fish leap outside the water and hang to a clinging leaf
  • Female lays eggs on the leaf and the process happens multiple times
  • Daddy Fish drops down into the water and splashes the eggs with water until they hatch –> force of the water causes them to hatch

Asexual Reproduction

65
Q

Kangaroos

A
  • Mother produces up to three young at a time
  • One in pouch attached to nipple
  • One out of pouch still drinking milk
  • One fertilised ovum
  • Milk production lasts longer so the kangaroo undergoes embryonic diapause to delay development of zygote until oldest doesn’t need any more milk
  • In drought periods kangaroos stop reproducing until rain comes and triggers a hormonal response
66
Q

Compare Self Pollination & Cross Pollination

A

Genetic Diversity:
- Self Pollination: Low genetic diversity as offspring is genetically similar to the parent plant
- Cross Pollination: Higher genetic diversity as offspring has genes from both parents

Pollination agents:
- Self Pollination:Most often don’t require any as the pollen is transferred within the same plant
- Cross Pollination:Relies on abiotic or biotic agents to carry pollen from one plant to another

Energy required:

  • Self Pollination:Less energy required as attracting features like petals are not required
  • Cross Pollination:More energy required to attract pollinators to look or scent
67
Q

What are the types of asexual reproduction in plants?

A
  • Vegetative Porpogation (Cuttings)
  • Runners
  • Rhizomes
  • Suckers
  • Tubers
  • Bulbs
68
Q

Why is asexual reproduction preferred in plants over sexual reproduction?

In most cases

A

The organism is already perfectly suited to the environment and reproduction occurs much quicker

69
Q

Runners

A

Special stem called runner grows horizontal to the plant and have nodes where buds are formed which grow into new plants
- Nodes are formed at intervals along the runner whcih form roots and shoots when it touches the ground
- Stolon breaks away completely once the plant has matured, leaving a new plant

70
Q
A

Biology Mod 5 Heredity (2 decks)

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