module 6 (3) Flashcards
(20 cards)
how does lack of light cause chlorosis
plants turn off chlorophyll production to conserve resources
how does mineral deficiencies cause chlorosis
cant make chlorophyll
how do viral infections cause chlorosis
affect metabolism
how is genetic variation produced
created by the versions of genes you inherit from your parents
define genotype
for most genes, two alleles are inherited
combination of alleles = genotype
define the dominant allele
always be expressed if present
define the recessive allele
expressed if two copies are present
define codominance
occurs when two different alleles code for a gene
both alleles are expressed
how does the Y chromosome cause male development
carries genes cause embryo to develop as male
define dihybrid
2 different characteristics caused by 2 genes located on different pairs of homologous chromosomes
why does the genetic cross differ from the actual ratio
random fertilisation
genes being studied on same chromosome are linked, so if no crossing over = alleles inherited together
define autosomal linkage
genes linked are found on other pairs of chromosomes
how are linked genes inherited
as one unit
what is the formula for recombinant frequency
no. of recombinant offspring / total number of offspring
if there is 50%+ recombinant frequency, is there linkage
no
define epistatis
interaction of genes at different loci
> gene regulation
what is dominant epistatis
dominant allele results in gene having affect on another gene
define disruptive selection
extreme phenotypes are selected
what are problems with inbreeding
likely to have recessive allele
so higher chance of genetic diseases
affects ability to survive + reproduce
what’s the difference between seed and gene banks
seed bank = seeds
gene banks = biological samples
