Chapter 16: Reproduction Flashcards
Describe asexual reproduction
a process resulting in the production of genetically identical offspring from one parent
Advantage of Asexual Reproduction in plants and population
Population
-Population can increase rapidly.
-Can exploit a suitable habitat quickly.
Crop
-Only one parent needed.
-Rapid colonization of favorable environments
Disadvantage of Asexual Reproduction in plants and population
Population
-Does not lead to variation in a population.
-The species may only suited to one habitat.
-Disease may affect all individuals in a population.
Crop
-No variation, so any change in environmental conditions will affect all individuals (ex. disease)
Describe sexual reproduction
a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other
Describe fertilisation
the fusion of the nuclei of gametes
Are gametes and zygote haploid or diploid
nuclei of gametes are haploid and that the nucleus of a zygote is diploid
Advantage of sexual reproduction
- produces combination of greater survival value
- new varieties can be created = may have resistance to disease
- in plants, seeds are produced, which allow dispersal away from parent plant, reducing competition
Disadvantage of sexual reproduction
- usually two parents are needed
- growth of a new plant to maturity from a seed is slow
Structure of flower
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Function of sepal
to protect the flower bud as it develops
Function of petals
attract insects for pollination
Function of stamen
Stamens are the male reproductive organs which are responsible for producing and dispersing pollen
Function of filament
carry nutrients to the anther for the development of the anther and pollen grains.
Function of anther
to produce and provide the pollen
Function of carpel
The carpel is the female reproductive part of the plant. It facilitate reproduction in flowering plants.
Function of style
generates the pollen tube but also prevents incompatible pollen from entering the ovary.
Function of stigma
The stigma is a sticky surface that catches the pollen during pollination.
Function of ovary
prepare the ovules for fertilization, protect developing zygotes, and develop into a seed-bearing fruit.
Function of ovule
The ovules are the structures that eventually develop into seeds; Each ovule contains an ovum
describe the anthers and stigmas of a wind-pollinated flower
anthers: external position and long filaments
The stigmas are comparatively large and protruding ( sticking out), sometimes branched and often feathery.
Distinguish between the pollen grains of insect-pollinated and wind-pollinated flowers
In wind-pollinated flowers pollen: spiky,
heavier,
larger,
small amounts
In insect-pollinated flowers pollen: smooth,
lightweight,
small,
large amounts
Describe pollination
the transfer of pollen grains from an anther to a stigma
Describe self-pollination
the transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant
Describe cross-pollination
the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species
Effects of self pollination on its population
- reduced diversity
- increased competition between plants;
- little ability to evolve
- no pollinators required
Effect of cross pollination in its population
- allows, genetic diversity;
- resistance to disease;
- evolve;
- relies on pollinators
When does fertilization occur
when a pollen nucleus fuses with a nucleus in an ovule
The pathway of pollen to fertilization
After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary.
The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule.
Describe the structural adaptations of insect-pollinated flowers
- nectar;
- spiky,pollen;
- sticky stigma;
- colourful petals
Describe the structural adaptations of wind-pollinated flowers
- petals dull;
- large amounts of pollen, released;
- small, pollen;
- smooth pollen
describe the environmental conditions that affect germination of seeds
water: for softening testa / seed coat + activation of enzymes + solvent;
oxygen: for respiration
suitable temperature: for optimum temperature for enzymes; break down food stores
Describe the growth of the pollen tube and its entry into the ovule followed by fertilisation
After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary. The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule.
Male reproduction system
testes, scrotum, sperm ducts, prostate gland, urethra and penis
Female reproductive system
ovaries, oviducts, uterus, cervix and vagina
What is fertilization
the fusion of the nuclei from a male gamete (sperm) and a female gamete (egg cell)
Explain the adaptive features of sperm
flagellum: for movement and swimming; mitochondria: to provide energy from respiration for movement;
enzymes in the acrosome: to dig through the jelly coat and membrane of an egg cell
Explain the adaptive features of egg cells
energy stores: provides energy to divide the zygote;
the jelly coat that changes at fertilisation: to form a barrier after fertilisation to prevent other sperm from entering the cell
Compare male and female gametes
egg cell much larger than sperm;
sperm is capable of locomotion while egg cannot;
sperm produced everyday in huge numbers, while egg released once a month
State what happens to the zygote in early development
in early development, the zygote forms an embryo which is a ball of cells that implants into the lining of the uterus
Function of umbilical cord in development of fetus
Transfer substances ( oxygen and nutrients) between placenta and fetus
Function of placenta in development of fetus
supplies, nutrients
removes waste
acts as a barrier against toxins or pathogens
Function of amniotic sac and amniotic fluid
maintains temperature; (mechanical) protection;
provides support (of the fetus); prevents infections;
allows movement (of the fetus);
(movement) allows for development of bones and muscles;
fetal drinking; lubrication
Describe the function of the placenta and umbilical cord
exchange of dissolved nutrients, gases and excretory products between the blood of the mother and the blood of the fetus
Can everything be blocked by placenta
Some pathogens and toxins can pass across the placenta and affect the fetus
roles of testosterone in the development and regulation of secondary sexual characteristics during puberty
voice deepens;
growth spurt;
sperm, production;
facial hair grows;
Describe the roles of oestrogen in the development and regulation of secondary sexual characteristics during puberty
breasts grow;
pubic hair growth
growth spurt;
menstrual cycle begins
Describe the menstrual cycle in terms of changes in the ovaries and in the lining of the uterus
days 1-5: uterus lining lost;
days 8-14: uterus lining,increases;
day 14: egg cell is released;
Describe the sites of production of oestrogen and progesterone in the menstrual cycle and in pregnancy
ovary
Explain the role of oestrogen in controlling the menstrual cycle and pregnancy
repair of the lining of uterus;
womb thickening;
development;
prepares for, implantation;
release of LH;
inhibits release of FSH;
stops, release, of more eggs;
causes change in cervical mucus
Explain the role of LH in controlling the menstrual cycle and pregnancy
maintains the thickness of the lining of the uterus during pregnancy;
ovulation gland
Explain the role of FSH in controlling the menstrual cycle and pregnancy
FSH stimulates follicle;
to grow;
to secrete oestrogen;
maturation of egg;
subsequent effect on LH at ovulation;
low FSH after ovulation, prevents further follicle stimulation;
Explain the role of progesterone in controlling the menstrual cycle and pregnancy
maintains, uterine lining;
inhibits, FSH / LH (release)
Describe a sexually transmitted infection (STI)
an infection that is transmitted through sexual contact
what Is the human immunodeficiency virus (HIV)
is a pathogen that causes an STI
What might HIV infection lead to
AIDS
Describe the methods of transmission of HIV
blood to blood contact ;
sharing needles;
breastfeeding;
transfusions;
Explain how the spread of STIs is controlled
use of, condoms;
tracing of sexual contacts;
testing for STIs;
treating infections;
