L4: Sex, reproduction & development

Question 1

what is the purpose of reproduction?

Answer 1

to replace individuals, allow for adaptations, and transmit genetic material, allowing populations to outlive individuals

Question 2

compare asexual vs sexual reproduction

Answer 2

sexual occurs with the fusion of a male gamete & female gamete, & offspring are genetically unique
asexual occurs from one parent, without fusion of gametes, & offspring are clones

Question 3

which type of reproduction is advantageous in stable conditions?

Answer 3

asexual

Question 4

identify the 4 types of asexual reproduction

Answer 4

• fission (separation of parent into 2 or more offspring)
• budding (new individuals from outgrowths of existing ones)
• fragmentation (breaking of body into pieces & develop into adults)
• gemmulation (formation of new individual form aggregation of cells surrounded by resistant capsule (dead parent)

Question 5

identify & describe the process where gametes are formed

Answer 5

meiosis - cell divides once, but splits twice, so each cell has half the genetic material from the parent cell

Question 6

identify two exceptions to bi-parental sexual reproduction

Answer 6

• hermaphroditism (both female & male organs in same individual)
• parthenogenesis (development of new individual from unfertilised egg)

Question 7

identify the advantages of meiosis allowing for recombination of genes

Answer 7

increases:
- variation in offspring
- reproductive success of parents in changing environment
- rate of adaptation
possible elimination of harmful genes while still allowing survival

Question 8

decribe spermatozoa / sperm

Answer 8

the male gamete
motile
consists of head (containing nucleus) & flagella to allow swimming

Question 9

describe ovum / egg

Answer 9

female gamete
larger, energetically expensive, & fewer in number
contains yolk (nutrients for growing individual)

Question 11

identify the purpose of reproductive systems

Answer 11

to produce & deliver gametes through gonads (ovaries or testes)

Question 12

what is a monotreme?

Answer 12

animal with a single opening for digestive, excretory & reproductive system

Question 13

. . . in reproductive organ shapes must mean organs of the opposite sex must be diverse

Answer 13

diversity

Question 14

compare external fertilisation vs internal fertilisation

Answer 14

external - eggs are shed by female & fertilised by male in external environment
internal - fertilisation occurs within female reproductive tract & requires behaviour interactions & compatible organs

Question 15

identify how timing of fertilisation is facilitated

Answer 15

• hormones telling when female is ovulating
• pheromones telling when fertile
• reproductive cycle

Question 16

identify the term for the release of mature eggs at midpoint of a female cycle

Answer 16

ovulation

Question 17

how can readiness to mate be indicated?

Answer 17

behaviours & displays

Question 18

embryos require an . . . environment to develop

Answer 18

aqueous

Question 19

identify the 5 steps to complete fertilisation

Answer 19

1. contact (sperm contacts egg’s jelly coat)
2. acrosomal reaction (sperm bind to egg, egg receptors recognise same species of sperm)
3. fusion (closing off egg to other sperm)
4. cortical reaction (sperm inside egg)
5. entry of sperm nucleus (dna synthesis & cell division)

Question 20

identify the 5 stages of embryogenesis

Answer 20

1. cell division / cleavage
2. body axis formation
3. tissue development / gastrulation
4. organ development / organogenesis
5. cell differentiation / specialisation

Question 21

what occurs during the process of cleavage?

Answer 21

rapid mitotic cell divisions without cell growth
first 5-7 divisions produce blastula (hollow ball of cells) surrounding the blastocoel (fluid-filled cavity)

Question 22

describe the body axis formation

Answer 22

determined by cleavage patterns, the migration of these forms the different symmetry body types

Question 23

compare the animal pole vs vegetal pole

Answer 23

animal pole - region of zygote where cleavage division is rapid, less yolk, smaller blastomeres
vegetal - slow division, more yolk, larger blastomeres

Question 24

describe the process of gastrulation

Answer 24

formation of 3 embryonic germ layers
- ectoderm (outer) mesoderm (middle) & endoderm (inner, lines digestive tract)

Question 25

describe the process of cell specialisation

Answer 25

genes release cues telling cells where to grow & divide, to form organs & limbs