biology Flashcards
define asexual and sexual reproduction
Asexual reproduction → generates offspring that are genetically identical to a single parent
Sexual reproduction → two parents contribute genetic information to produce unique offspring, creating variation.
penis
delivers sperm through the urethra into the female reproductive tract
bladder
muscular sac that stores urine until it is released through urethra
prostate gland
surrounds a portion of the urethra and produces some of the fluid in semen to nourish sperm
testes
produce sperm and the male sex hormone testosterone
scrotum
contains the testes and epididymis and controls the temperature of the testes
seminal vesicle
secretes a sugar-rich, thick fluid that nourishes the sperm
urethra
tube that carries semen and urine out of penis
vas deferens
thin muscular tube transports the sperm from the epididymis to the urethra
epididymis
a narrow tube where sperm is stored
vagina
tube that connects uterus to outside of body
ovary
make eggs (ovum/ova) and hormones like oestrogen and progesterone
fallopian tube
A tub that carries eggs from the ovaries to the uterus. Fertilisation happens here
cervix
narrow ring of muscle that opens into the vagina from the uterus
uterus
a hollow, pear-shaped organ with a muscular wall where foetus develops
uterine wall
thickens during the menstrual cycle in preparation for implantation of fertilised egg
pros & cons of asexual and sexual reproduction
asexual
Pros: no mating required, quick
Cons: low genetic variation, population is threatened when under stress
sexual
Pros: genetic variation, helps population survive when under stress
Cons: takes a long time, requires two individuals to mate
define gene
DNA transferred from a parent to offspring, determining characteristics, provides instructions for building a specific protein
mitosis
Prophase: Chromatin forms chromosomes (made of DNA & protein), nucleus disappears, spindle apparatus forms.
Metaphase: chromosomes line up down the middle of the cell
Anaphase: sister chromosomes are separated and moved to opposite ends of the cell
Telophase: reverse of prophase. Each new cell will start a new life in interphase. Chromosomes form into chromatin, nucleus returns, spindle breaks down.
compare mitosis & meiosis (similarities & differences)
both use PMAT, cell division and and begin with a diploid cell
mitosis:
makes somatic cells (body)
growth, repair, replacement
2 identical daughter cells
46 chromosomes
diploid
meiosis
sex (gamete) cells
sexual reproduction & genetic diversity
4 daughter cells
23 chromosomes
haploid
crossing over
meiosis
Prophase I: chromosomes line up with their homologous pairs and cross over, transferring genetic information and making recombinant chromosomes.
Metaphase I: Chromosomes in middle of the cell in pairs (different from mitosis)
Anaphase I: chromosome pairs pulled apart by spindle fibres
Telophase I: 2 newly formed nuclei, 2 new cells
Meiosis II, prophase II: spindles form
Metaphase II: chromosomes line up in single file, not pairs
Anaphase II: chromatids are pulled away by spindle fibres
Telophase II: nuclei reforms, 2 cells turn into 4 cells
define allele
different versions of a gene found in the same chromosome
define dominant & recessive
Dominant → allele overruled the other allele (recessive), always expressed if you have a copy
Recessive → a gene masked by a dominant gene, only expressed if you are
define genotype & phenotype
Genotype → combination of alleles you have
Phenotype → expression of genotype (e.g. brown hair)
define homozygous and heterozygous
Homozygous → two copies of the gene are the same
Heterozygous → two copies of the gene are different
define co dominance
both alleles of a gene are equally expressed in the phenotype, without one overshadowing the other.
define sex linkage
Sex linkage is when a gene is found on a sex chromosome (X or Y), so its traits are passed on differently in males and females.
outline the process of DNA replication
DNA replication is the process where the DNA molecule unwinds, and each strand serves as a template for creating a new complementary strand, resulting in two identical DNA molecules.
define mutation
change in the base sequence of DNA
distinguish between DNA and RNA
DNA: stores and transmits genetic information in the form of a double-stranded helix
RNA: single-stranded molecule that helps carry out the instructions encoded in DNA
define evolution
any change in the genetic traits in a population over many generations via variation, reproduction & natural selection
define natural selection
- Variation
- Competition
- Survival of the fittest
- Reproduction
- Population change
Define fossil
reserved remains of ancient organisms.
common ancestor
an ancestral group of organisms that is shared by multiple lineages (an ancestor they have in common)
