model ppq answers

Formation of new alleles

• mutation

• Change in base sequence of DNA

• Caused by ionizing radiation

Artificial selection

• Select individual organism that shows desirable feature

• Cross individuals to produce next generation

• Select offspring that shows desirable the desirable feature

• Repeat for many generations

Natural selection vs artificial

• in natural, selection pressure comes from environment

• Better adapted individuals survive and reproduce

• Produce characteristics suitable for new environment

Advantage of developing pest resistant plants

• less pesticides used

• Less contamination of food with pesticides

• Less pollution

• Higher quality of crop

• Less risk to pollinators

• Improve health of farm workers

• Increase biodiversity

Why eat from lower tropic level

• energy lost through each tropic level

• Through excretion, movement, indigestible parts, metabolism

• X is at lover tropic level than y

Digestion of fat

• physical digestion

• Emulsified by bile

• Increases surface area of fats for enzymes

• Lipase used to digest

• Secreted by pancreas

• Break fat down into glycerol & fatty acids

• Absorbed by lacteals in microvilli

• in small intestine

Adv & dis of asexual reproduction

Adv:

• shorter time

• Offspring adapted to environment

• Doesn’t rely on pollinators - surely occurs

Dis

• reduces genetic variation

• Susceptible to disease

Cross pollination

Pollen grains from anther to stigma of a different plant of the same species

Processes after pollination

• pollen tube develops from pollen grain

• Releases enzymes

• Grows down style into ovary

• Nucleus travels down pollen tube into ovule

• Fertilization - male and female nuclei fuse

• Forms zygote

Making proteins

• mRNA is copy of gene made in nucleus

• DNA remains in nucleus

• mRNA moves to ribosome

• mRNA passes through ribosome - which assembles amino acid into protein

• Sequence of amino acid determined by base sequence in mRNA

Why conservation programme

• increase biodiversity

• Maintain food web

• Maintain source for food/drugs

• Protect vulnerable habitat

• Would affect nutrient cycles

Artificial insemination

• male chosen from different program to maximize genetic variation

• Sperm screened and frozen

• Females given injection to induce ovulation

• Sperm placed in uterus at appropriate time for ovulation

Temp too high - no product (enzyme)

• active site denatured

• Change shape

• Active site does not fit/bind to /not complementary to substrate

• Can’t break down …

Sense organ

• Group of receptor cells → detect/respond to stimuli/change in surroundings

Eye accomodation - near object

• Ciliary muscle contracts

• Suspensions ligament slackens

• Lens becomes more convex

• More refraction

• Light focused onto retina/fovea

Distribution & function of rods and cones

Distribution:

• both on retina

• High conc. cones, no rods in fovea

• No rods or cones in blind spot

Function

• light receptors

• Rods → respond to low light intensity, give night vision AND greyscale

• Cones → respond to high light intensity, give colour vision

Break down of starch

• Mechanical digestion

  • Using teeth/churning in stomach

  • Increase surface area for enzyme activity

• Chemical digestion

  • Breakdown of insoluble molecules into smaller, soluble molecules (using enzymes)

• Amylase secreted by salivary glands/pancreas

• Amylase breaks down starch to maltose

• Maltase in epithelium of small intestine

• Maltase breaks down maltose to glucose

• Both pH 7(neutral)

Advantage of sexual reproduction

• Genetic variation

• Different combinations of DNA

• Natural selection/adaption in response to changing environment

  • Adaption to: new climate, disease, predator

• Reduce chances of extinction

Function of cervix

• Dilates in process of birth

Function of placenta

• gas exchange

• Transfer:

  • Nutrients from maternal to fetus

  • Antibodies from maternal to fetus

  • Excretory products from fetus to maternal

• By diffusion

• Produces hormones

• Separates fetal & maternal blood supply

Function of amniotic sac

• Provides support to fetus

• Protect fetus from shock

• Maintains temperature

• Provides sterile environment

• Allows development of bones & muscles

Pathway of products of protein digestion from villi to liver

• amino acids move into capillaries

• Carried into blood plasma

• Travel to the hepatic portal vein

Yeast kingdom

Fungi

Vein description

• Wide lumen

• Thin walls

• Valves

• Elastic fibers

• Lined by single layer of cells

Evidence for double circulation

• 2 sides (left & right)

• Blood passes through heart twice in one complete circuit

• Circuit = heart → lung, heart → body

Double circulation advantage

• Septum, separates oxygenated and deoxygenated

• Efficient supply of oxygen & nutrients

• Lower oressure in circuit

• Prevent damage to lungs

• Allow more time for gas exchange

• Allow higher pressure in body

• Ensure efficient blood supply

• Allow filtration in kidneys

• Allow high rate of respiration