chapter 9 - reproduction

Question 1

genetic diversity of a population

Answer 1

the amount of genetic variation

Question 2

gene pool

Answer 2

the sum of all the different genes and alleles that are present in a population and species
-influenced and maintained by a number of naturally occurring mechanisms

Question 3

why is genetic diversity important?

Answer 3

-protects longevity of species by guarding against disadvantageous environmental changes
-larger the gene pool, greater the resilience to environmental change
-populations with more alleles are more likely to have alleles that are already adapted to new environment

Question 4

sexual reproduction

Answer 4

-involves fusion of two haploid gametes to form a single, genetically unique, diploid zygote

Question 5

oviparity

Answer 5

-eggs are released into the external environment, where the embryo develops
-occurs in frogs, snakes, lizards, hens, ducks etc

Question 6

viviparity

Answer 6

-embryo develops inside mother’s body and is born after a period of gestation
-occurs in humans, bears, giraffes, cattle, salamanders etc

Question 7

reproduction of angiosperms (pollination)

Answer 7

-pollen is collected by stigma of flower and fuses with ovule
-embryo that develops will become a seed
-occurs in plants

Question 8

advantages of sexual reproduction

Answer 8

-increases genetic diversity by allowing for recombinant offspring
-improving genetic resistance by promoting presence of different alleles
-combining genetic material reduces chances of offspring inheriting genetic disorder

Question 9

disadvantages of sexual reproduction

Answer 9

-cost of male progeny
-time, energy, and resources required to attract and find a mate
-risk of stds
-risk of losing offspring to outside influences

Question 10

asexual reproduction

Answer 10

-offspring/daughter cells are clones of each other and of parent

Question 11

types of asexual reproduction

Answer 11

-binary fission
-budding
-fragmentation
-vegetative propagation
-sporogenesis
-parthenogenesis

Question 12

binary fission

Answer 12

-one organism divides into two identical organisms
-occurs in simple prokaryotic organisms

Question 13

budding

Answer 13

-involves formation of a bud, which forms due to increased cell growth, then breaks away from main organism, where it can develop into separate organism
-occurs in yeast, sponges, jellyfish, coral, worms

Question 14

fragmentation

Answer 14

-involves parent organism breaking into separate fragments, each of which is capable into developing in separate organism
-occurs in simple eukaryotes (worms? and starfish) and many plant species

Question 15

vegetative propagation

Answer 15

-allows a plant to reproduce without seeds
-part of plant breaks away from original plant, then independently grows into new plant

Question 16

sporogenesis

Answer 16

-involves formation of spores (found on surface on organisms), which are dispersed into the surroundings where they grow into larger organisms
-occurs in many plants, fungi, algae, moulds

Question 17

parthenogenesis

Answer 17

-an embryo can develop from a female gamete alone
-results in eggs produced via mitosis and develop into organism identical to female parent
-rare and occurs in less than 0.1% of all vertebrate species

Question 18

advantages of asexual reproduction

Answer 18

-populations grow faster than sexually reproducing ones
-offspring identical to parent - important as organism’s phenotype is fine-tuned to survive environment
-doesn’t require mate
-requires little parental investment

Question 19

disadvantages of asexual reproduction

Answer 19

-genetic diversity is low, populations may suffer from rapid environmental change

Question 20

reproductive cloning in animals

Answer 20

-somatic cell transfer
-embryo splitting

Question 21

somatic cell transfer (scnt)

Answer 21

-involves donated egg cells and donated somatic cell
-offspring is genetically identical to donated somatic cell

Question 22

steps of scnt

Answer 22

1. enucleation - removal/destruction of nucleus from donated egg cell to produce an enucleated egg cell
2. extraction - donated somatic cell’s nucleus is extracted
3. insertion - somatic cell’s nucleus is inserted into enucleated egg cell
4. development - cell begins to divide and develop into an embryo, which is implanted into a surrogate mother

Question 23

applications of scnt

Answer 23

-has been used to clone living and recently deceased animals
-dolly the sheep in 1997

Question 24

complications of scnt

Answer 24

-animal suffering
-human cloning - illegal in many countries
-premature aging

Question 25

embryo splitting

Answer 25

-embryos are split artificially for agricultural applications
-embryos are implanted into surrogate mothers where embryo development is completed - clone is genetically identical to original embryo
-ideal splitting is between 6-8 cells

Question 26

applications of embryo splitting

Answer 26

-in agriculture, is conducted with ivf to fertilise offspring with desirable traits

Question 27

complications of embryo splitting

Answer 27

-alteration of embryos
-decreased genetic diversity
-research animals

Question 28

reproductive cloning in plants

Answer 28

-plant tissue culturing
-plant cutting
-plant grafting

Question 29

plant tissue culturing (micropropagation)

Answer 29

-plant cells are grown on a nutrient culture medium, aspects of environment are controlled (lab)
-as it develops a callus begins to form
-callus then can be separated into several cultures and stimulated to grow into clones of original plant

Question 30

applications of plant tissue culturing

Answer 30

-produce plants all year round in disease-free environment
-clones for agricultural research, clone rare plants

Question 31

plant cuttings

Answer 31

-obtained by cutting off fragment of plant
-fragment is placed in soil/water and will grow under right conditions, producing clone of original plant

Question 32

plant grafting

Answer 32

-involves attaching stem of one plant (scion) to stem of another plant with an already developed root system (rootstock)
-eventually, these 2 sections will grow and fuse together, producing clone of plant that scion was taking

Question 33

applications of cutting and grafting

Answer 33

-relatively old cloning techniques
-allow for rapid growth of desired plant, however grafting often helps provide plants with cold tolerance, resistance to disease, and increased productivity

Question 34

biological implications of plant cloning

Answer 34

-unrestrained cloning could lead to reduction in genetic diversity
-cloned population is more susceptible to disease, pests, and environmental changes