Biology Paper 2 IGCSE edexcel VOCAB

PH and enzyme function

If too high or too low it can cause the enzymes to denature but often the enzymes optimum PH is 7 (not in the stomach!!)

Calorimetry. What is it and how can you test for it?

Calorimetry is the process of burning food to see how much energy it contains. Weigh food sample and skewer on mounted needle. Hold under test tube of water held with a clamp and set on fire. Continue to do this until the food no longer sets on fire. Measure the temp of the water again.

Energy in food=

Mass of water(in grams) x temperature change of water (in degrees Celsius) x 4.2

Energy per gram in food=

Energy in food / mass of food

How are root hair cells adapted

Millions of hairs, big surface area for osmosis

Phloem

Transport sugars such as amino acids and sucrose from the leaves to other parts of plant.

Translocation

The transport of sucrose and amino acids in the phloem, from regions of production to regions of storage or use

Pepsin

Enzyme made in stomach that breaks down proteins into smaller polypeptide chains. It works best at pH 2/low pH

Turgid cells

When a plan is well watered all it's cells draw in water by osmosis to become plump and swollen

Turgor pressure is

The contents of the cell push against the cell wall. It helps to support plant tissue

Flaccid cells

When there's no water in the soil so a plant starts to wilt and therefore lose water and turgor pressure.

Why doesn't a plant loose its shape?

It has inelastic cell walls to keep things in position

A balanced diet has six essential nutrients. What are they?

Carbohydrates, proteins, lipids, vitamins, minerals and water (fibre also keeps the gut in good order)

What do energy requirements depend on?

Activity level, age and pregnancy

Carbon dioxide production can be detected using

Hydrogen carbonate solution. Orange at normal levels, yellow at higher levels and purple at lower levels.

Describe an experiment to detect the production of carbon dioxide.

Soak dried beans in water for two days. This will start germination and therefore respiration. Boil a similar sized second bunch of beans to act as control. Put hydrogen carbonate indicator into two test tubes and place a gauze platform into tubes and place beans on this. Seal with rubber bung and leave for an hour. Repairing tube will have turned indicator yellow as there is increased production of CO2

Describe an experiment measuring the heat produced by respiration.

Prepare 2 sets of beans and add each set to a vacuum flask making sure some air left. Place thermometer in each and seal tops with Cotton wool. Record temperathre of each everyday for a week. When germinating beans respire they produce heat which causes temperature to increase

The net exchange of gases depends on

Light intensity

During the day plants

Release oxygen (from photosynthesis) and take in carbon dioxide (for photosynthesis)

At night plants

Gas exchange in flowering plants. What are the 7 things you need to carry out an experiment?

Hydrogen carbonate indicator, test tubes, bungs, leaves (same species,age...) light source, aluminium foil and gauze.

Platelets are

Cells that cause blood clotting.

Platelets are held together by a mesh called

Fibrin

Vaccination

Injects dead or inactive pathogens into your body so the body can react and therefore produce memory cells

Vasodilation

When you are too hot / blood vessels widen / hairs lie flat/ sweat

Vasoconstriction

When you're too cold/ little sweat/ blood vessels constrict/ shiver/ hairs stand on end

Germination depends on

Water/oxygen/temperature

Germinating seeds get energy from

Food stores

The placenta

Develops once embryo has implanted and allows the exchange of food oxygen and waste

Amniotic fluid

Protects the embryo against knocks and bumps

Embryo develops

During pregnancy and implants into the uterus

Codominant alleles

BOTH ALLELES ARE CAPITALS (not recessive)

Mutations can

Happen spontaneously and can be increased risk by ionising radiation and mutagens

Mutations are

A random change in an organisms DNA

The water cycle

Evaporation, transpiration, condensation, precipitation

Nitrifying bacteria

Turn ammonium ions in decaying matter into nitrates (nitrification)

Nitrogen fixing bacteria

Turn atmospheric nitrogen into nitrogen compounds that plants can use. In the roots and soil

Denitrifying bacteria

Turn nitrates back into nitrogen gas. This is no Benefit to living organisms

Decomposers

Break down proteins in rotting plants and animals and urea in animal waste turning them into ammonia. Forms ammonium ions in the soil

Nitrogen fixation happens by

Lightning or nitrogen fixing bacteria

What bacteria is used in yoghurt making?

Lactobacillus bulgaricus

Fermenters are where…

Microorganisms are grown

Transgenic - what does it mean?

They contain genes transferred from another species

Advantages to cloning

Transgenic cloning/ helpful/ genetic characteristics are always passed on

Disadvantages of cloning

No long term evidence/ difficult/ time consuming/ expensive