5.1.1 Flashcards
Heredity - Reproduction
what is sexual reproduction
key words, give an example
- process of forming a new organism from the* fusion *of the offspring’s parents’ gametes (sperm and egg)
- meiosis plays a big role
- humans and turtles examples
what are organisms called when they have both sex cells in one and give examples
hermaphrodites
(flowering plants, earthworms)
what is asexual reproduction and give example
- forming offspring from one parent
- mitosis
- offspring is a clone of parent : identical
hydra, amoeba
wat r pros/cons for sexual reproduction
pro -
* high genetic variability
* adaptations r managed
* speeds up evolution
con
* energy costly
* mating takes time/finding mate
* usually sacrifices the fitness of one sex to the other (Amensalism)
pros/cons of asexual reproduction
pros
* saves energy
* courtship aint issue/matin
* increase in fitness^
cons
* low genetic variability
* adaptation to selection pressures will be difficult if traits rnt favourable 4 speciees
How sexual and asexual reproduction processes allow parents’ genetic information to be passed on to their offspring, and thus, ensuring the continuity of the species?
-genetic info is passed onto the next generation
-creates variation
-reporduction increases population size
somatic vs non-somatic?
somatic - any cell other than reproductive
non-somatic : opposite
define evolution
Evolution is the change in living organism’s genetic information, favourable characteristics and phenotypes over many generations.
the stages of darwins theory of evolution? the six
- genetic variation in population
- majority of population have favourable traits
- sudden change in environmental conditions
- organisms w favourable characteristics will pass it on, while others with less favourable traits wil decline in numbers
- organisms that r favourable wil reproduce successfully
- new population full of favourable traits other than mutations
what is an environmental change called
environmental agent
what r three forms favourable characteristics can come in
physical, physiological and behavioural
what are main sources of variation?
- adaptations that r inherited
- mutations
- independent assortment and random segregation during meiosis
what are key examples of asexual reproduction and give example of how it formed
fungi - spores - zygomycota
bacteria - binary fission- coli
protists - budding- protozoa
protists-binary fission - amoeba
animals - parthenogenesis - bees
plants - frangmentation, runners, bulbs - mosses, strawberries, onions
what r key examples of sexual reproduction and give examples
fungi-sexual-spores- mushroom
animals - internal/external fertilisation - humans
plants - self/cross pollination - sunflowers
compare internal/external fertilisation
Internal – involves the fusion of male and female gametes within a parent’s body.
* terrestrial animals
* protects gametes from dehydration
* protects the fertilised eggs and developing young from immediate predation.
External - involves the fusion of male and female gametes outside a parent’s body.
* Tends to occur between aquatic animals
what is the main goal for fertilisation generally
the gametes, each of which is a single haploid cell surrounded by a cell membrane, must meet and not dehydrate in the process
what r the three things that intensify the chances of successful external fertilisation
- synchronisation of reproductive cycles
- mating behaviours
- release of gametes
This means that less time and energy is required of parents, but a larger number of gametes must be produced to ensure that some young survive.
what is parthenogenesis and what is the plant and animals called that possess this
Process whereby an unfertilised egg develops into a functional offspring. This is a form of asexual reproduction in animals, mainly bees.
- in which a female can produce an embryo without fertilizing an egg with sperm.
- plants = apomixis
- animals = parthenogenesis
what is pollination in simple words
Pollination is referred to as the process where the pollen is successfully transferred to the stigma of another plant.
what r the male parts of the plant, the neutral parts, and femal eparts
female - stigma, style, ovary, the whole thing is carpel
male - anther, filament
neutral - sepal, petal, receptacle
now describe the process of seual pollination
- Once the pollen is on the stigma, it can grow a pollen tube
- The pollen tube runs down the style of the plant and eventually into the ovary of the plant.
- The ovary of the plant produces the ovules (the female gametes).
- Fertilisation occurs in the ovule where the pollen can fertilise the ovule
- A zygote is then formed through the fertilised ovule (the seed)
- This fertilised ovule is called a seed which contains the zygote and will develop into an embryo
what does the surronding space of the ovule become most commonly
a fruit
what are the 2 main purposes for pollen grains produced by male
- pollen fertilisatises the two polar nuclei inside ovule which develops into endosperm
- it fertilises the ovum inside the ovule. the ovum is basically a seed which contains the zygote thatll grow
differentiate between self/cross pollination
cross - Involves the transfer of pollen, produced by anther to the stigma of another plant
- Involves two plants
- The pollen grain essentially contain the male gametes of the plant. This can be taken to another plant’s stigma through wind, water and animal pollination.
- Utilises external agent (wind, animals, ocean)
- Results in an offspring that is genetically different to its parents
self pollination - Does not involve an external agent. The stigma can reshape itself to enclose the stamen. This means that the pollen can be easily transferred onto the stigma. less genetic variation
what is vegetative propagation? give 3 examples
Vegetative propagation is a type of asexual reproduction that occurs in plants. It results in a parent producing a plant that is genetically identical.
Examples include :
* runners
* bulbs
* fragmentation
what is fragmentation, give example
When the original organism separates a small part of itself.
Example : occurs in starfish where a part of its body can be separated from its parent and the separated section can develop into a new starfish that is genetically identical to parent starfish via cell division
what are runners, give an example
stems extending from the plant and along the soil. At certain points along the runners, nodes can develop which extends to the soil, resulting in the formation of new plant roots at another area of the soil whereby a new strawberry plant can grow.
what are bulbs, give example
Bulbs are bud cells that are found underground. These buds can develop into new plants such as onions. When a new plant forms, the underground bulb provide nutrients to the plant for its survival.
what is budding, how does it work and what does it occur in?
Budding in fungi, protists
involves the parent cell developing a bud cell
- Once a bud develops, it undergoes cell division while still being attached to the parent. the parent’s nucleus’ DNA then replicates and nucleus divides equally, but the cytoplasm divides unequally (hence bud is smaller than parent).
- One copy of the DNA moves into the bud cell
- The bud separates from its parent fungus when it grows to a sufficient size to be able support itself independently.
- The now-separated bud undergoes further cell division to produce more bud cells. The result is yeast that is genetically identical to parent.
what is spore production, give examples n is it a/sexual?
both sexual and asex
-occurs asexualy in fungi
-occurs sexually in fungi
- spores are usually carried by the wind as they are light weight.
- spores germinates to form genetically identical fungus when environmental conditions are favourable.
- This typically involves the spores absorbing moisture and decaying organic matter
- This allows the cytoplasm to expand and the fungus developing into a mycelium whereas new spores can be produced.
what is binary fission how does it work and what does it occur in
occurs in bacteria, protists
-1. The copying of genetic material in bacterial chromosomes of the parent cell occurs
2. Each chromosome moves to each side of the cell
3. the elongation of the cell and cytokinesis which is the splitting of the cell membrane and cytoplasm of the cell into two daughter cells takes place
parent cell disappears at the end
what are pros/cons of internal fertilisation
pros of internal -
-protected, closed environment
-embryo protected
cons -
-greater energy expenditure
-less offspring produced at ONCE
-mother becomes vulnerable in pregnancy
pros/cons of external fertilisation
pros-
-little energy
-large numbers of offspring produced
-offspring can be spread widely, reducing competition w parent orgnaims
cons-
-majority of gametes r unfertilised
-offspring often not protected
what r mammals and what r three characteristics that define mammals
A mammal is a vertebrate animal
1. mammary glands; producing milk/lactation
2. endothermic : generates heat from metabolic processes
3. hair/fur
what r the three types of mammals
monotremes- egg laying mammals (platypus, echindas)
A marsupial is a mammal that raises its newborn offspring inside an external pouch at the front or underside of their bodies.
In contrast, a placental is a mammal that completes embryo development inside the mother, nourished by an organ called the placenta.
