Mistakes that haunt me

Correct this: asexual reproduction only requires one parent

Asexual reproduction only requires one parent CELL

Give the full answer: what will a build up of cholesterol in an artery leading to the leg do to muscle cells in the leg?

• Less oxygen and glucose will reach the muscle cells

• So they will carry out less aerobic respiration.

• They will carry out more anaerobic respiration

• And will release less energy.

• The anaerobic respiration will also cause a build-up of lactic acid, which will lower the pH of the cells

• Causing enzymes to denature

• So the muscle cells will DIE.

Roles of oestrogen

• Inhibits FSH

• Stimulates LH

• Is responsible for the development of secondary sexual characteristics

• Thickens the uterus lining

Evaluating a conclusion: what if they don’t give information on the types of people tested on

We do not know if they tested on people of the same age/sex/mass (and some things specific to the condition - e.g. CHD and smoking or exercise) etc., so the results could be unreliable.

Function of the umbilical cord

Connects the foetus to the placenta. It contains the umbilical artery (carrying blood containing carbon dioxide and urea out from the foetus) and the umbilical vein (carrying blood containing oxygen, glucose, amino acids, vitamins, minerals and antibodies into the foetus).

Why do seeds need a food store?

To provide glucose, for respiration, as they cannot photosynthesise to make this glucose, as they do not have any leaves.

4 factors required for germination and reasons

• Water - to activate enzymes

• Oxygen - for aerobic respiration

• Warmth - to provide the optimum temperature for enzymes

• Light - to activate plant growth regulators

Phrase better: placenta allows for carbon dioxide and urea to pass from foetal to maternal blood

The placenta allows for carbon dioxide and urea to be removed from foetal blood, as it diffuses into maternal blood

What passes from maternal to foetal blood

* Oxygen
* Glucose
* Amino acids
* Vitamins
* Minerals
* Antibodies

Improve: results are reliable if the experiment has been repeated many times …

AND THE RESULTS ARE SIMILAR

Why count heart rate over 15s, not a minute?

* There is less chance of losing count
* It is quicker to collect results
* The results of \[whatever you are testing\] may wear off quickly

When comparing results (3 marks)

* Compare overall - e.g. both increase/decrease
* Compare more specifically - e.g. smaller/greater increase/decrease
* Bring in data - useful to state the (approximate) multiple that the final value is of the first in one date set, then compare this multiple with the multiple for the other data set

In disease terms, what does a vector do

Transfers the pathogen from organism to organism

If there is a lack of circulation to a particular area (it may go blue), what does this mean in terms of blood vessels

VASOCONSTRICTON occurs: the narrowing of blood vessels. This means less blood, and therefore less oxygen, reaches that area

How does less transpiration affect a plant

MINERAL IONS are not transported to the requiring parts of the plant. The plant will have less nitrates, to produce amino acids, for proteins, for growth; less phosphates, which are needed for the production of ATP and nucleotides for DNA; less magnesium for chlorophyll (and less potassium to regulate osmosis)

Benedict’s reagent in a low concentration of glucose

Orange / yellow-green

Correct this: different amino acids in a protein lead to the formation of a different protein

Different amino acids in a protein lead to the formation of a protein with A DIFFERENT SHAPE

Why is meat that is low in fat healthy

There is less chance of coronary heart disease, as there is less chance of arteries being blocked by plaque, containing cholesterol.

If it is low in fat, it’s probably high in protein - this means that when it is digested, the body has more amino acids for growth and repair.

Mineral ions for bones

Calcium, PHOSPHATES

What is meant by the term “selective breeding”

When HUMANS breed organisms that have desired characteristics together

Menstrual hormone graph

LH and FSH have similar shapes, but LH is taller. Progesterone is high towards the end of the cycle, and oestrogen has the first major rise.

How do abnormal sperm affect the chances of fertilisation

Abnormal sperm may not be able to swim to the egg, to fertilise it, which would reduce chances of fertilisation.

Respiration experiment with locusts - control variables

• Same age, sex, species of locusts

• Same mass (more cells = more respiration)

• Temperature

• Size of flask (space to move)

• Time

• Volume and concentration of KOH

Why are fruits healthy

They contain vitamin C to prevent scurvy, and fibre to aid peristalsis

Word better: a better supply of oxygen means that the oxygen debt is repaid quicker

A better supply of oxygen means that there is better removal of lactic acid (so a person can run for longer)

Why does the aorta have a thicker wall than the capillary

• Aorta wall contains muscle and elastic tissue

• As it carries high pressure blood from the LEFT VENTRICLE

• Aorta needs to expand to carry this blood

• Needs to transport more blood than the capillary

Two structures in bacteria that contain DNA

Plasmid and CHROMOSOME

To test a leaf for starch

Place the leaf in boiling water for 30 seconds, to kill and preserve it, then place in boiling ethanol, to remove the chlorophyll - use a water bath for this, as it is unsafe to heat using a Bunsen burner as ethanol is highly flammable. Rinse the leaf with water to soften and rehydrate it, pat dry, then test it using iodine solution - if the iodine changes colour from orange-brown to blue black, starch is present.

How to measure the area of the green part of a variegated leaf

Trace around the leaf, then trace around the green part, using tracing paper. Put the tracing paper onto squared paper and count the number of squares. Do this for both sides of the leaf.

Why is the mean maximum lung volume for males and females similar at age 7, but different at age 25

At age 25, the males’ mean maximum lung value is greater than the females, as males grow more than females. There is a greater difference from puberty, as males continue to grow between the ages of 16-25.

Advantages of using artificial insemination in selective breeding (in cows, for example)

• Quicker and cheaper to transport semen than bulls

• Can impregnate the cows after the bull has died

• Can impregnate many cows

• Safer for cows

Can you say that osmosis requires a concentration gradient

YES!!

How do viruses differ from living organisms

• They are only able to reproduce inside living cells

• They have a protein coat

• They contain only one type of nucleic acid

• They are smaller than all living organisms

• They have no organelles (e.g. mitochondria)

• They have no cytoplasm

• They do not move

• They do not respire

• They have no sensitivity

• They do not grow

• They do not excrete

Why would the population of mice be higher in one year compared to others

• More food

• Due to warmer weather

• Fewer predators

• Less disease

• Higher birth rate

Why would an owl population be fairly constant for a number of years

• The birth rate was roughly equal to the death rate

• Owls have no predators

• They produce few offspring

• There is not enough food to maintain a higher population of owls

Why might e-cigarettes be less harmful than normal cigarettes

• There is less tar in e-cigarettes so there is less paralysis of cilia - this can cause chronic bronchitis

• There are fewer carcinogens

• There is less carbon monoxide in e-cigarettes

• There is less risk of heart disease

• It is easier to control nicotine levels

Apart from being addictive, why is nicotine a problem

It can increase risk of blood clots (and high blood pressure)

How could a scientist distinguish between conditions caused by polygenic or monohybrid inheritance in rats

• If the condition shows continuous variation, it is polygenic

• If it shows discontinuous variation, it is monohybrid

• If it is monohybrid the offspring will show a simple pattern - you can see this by looking at pedigree diagrams

Why would you wait until a bull is 4 years old to start collecting its semen

So that it has undergone puberty, and will be producing sperm

Uses of water in plants

• Reactant of photosynthesis

• Keeps plant cells turgid

• Transports mineral ions

• Water is needed for cooling

Correct this: impossible

IMPROBABLE

Hepatic portal vein

Transports blood containing digested food (glucose, amino acids, and fatty acids and glycerol) from the small intestine to the liver

Factors that increase the risk of coronary heart disease

• Diet containing too much saturated fat

• Obesity (carrying extra weight puts a strain on the heart)

• Lack of exercise

• Genetics

• Smoking

• High blood pressure (damages arteries because the force of blood against artery walls increases)

What are the effects of smoking on the lungs

• Tar paralyses cilia

• This leads to a build-up of mucus in the trachea

• Which can lead to a bacterial infection

• Which can lead to inflammation of the airways

• WHICH CAN LEAD TO COPD OR BRONCHITIS

• Chemicals in tar also cause emphysema

• Carcinogens in smoke cause lung cancer

Advantages of biological control

• No need to reapply

• Specific to the pest species

• No risk of resistance

• No bioaccumulation

• Lasts longer than pesticides

Correct this: measure the mass of plants

Weigh plants (using a mass balance)

How does having genetic variation in a population help it combat disease?

Mutations in DNA lead to different alleles forming. Some of these alleles give the organisms resistance to pathogens, which means that they will survive if the pathogen infects the population.

Respiring seeds experiment: why is cotton wool used at the mouth of the flask

To allow carbon dioxide to exit the flask, and oxygen to enter

Function of the digestive enzymes in the head of the sperm

Penetrates the membrane of the egg

Function of the nucleus of the sperm

Contains DNA - 23 chromosomes, to fuse with the nucleus of the egg to form a diploid nucleus

Imagine a calorimetry experiment with glucose. There is a waste tube for the products (going through the water in the calorimeter). Why is it coiled?

To increase the surface area, so that there is better transfer of heat to the water

For sewage etc dumped into a river, when talking about bacteria: not only do they decompose the sewage, using oxygen for aerobic respiration, but…

…the population of bacteria grows, so there are more bacteria, so they carry out more decomposition, and use up more oxygen for aerobic respiration.

All the ways in which the net can protect fish in a fish farm

Protects them from predators in the sea, from predatory birds, it keeps out other fish which could cause competition and spread disease

Causes of emphysema

Smoking, dust, fumes, genetics, bronchitis

Describe how fungi decompose organic material

Fungi are saprotrophs: they secrete enzymes that carry out extracellular digestion, from their hyphae, onto the organic material, and absorb the products of the digestion. These may include small, useful molecules such as water and carbon dioxide.

ALL the effects of increased carbon dioxide in the atmosphere

• Enhanced greenhouse effect

• Melting of ice caps

• Destruction of habitats

• Migration of species, including pests, and disease-carrying organisms

• Extinction of species, leading to disruption of food chains and webs

• Extreme weather events

Abiotic factor for plant growth - not light intensity, but:

SUNLIGHT

Biomass

The total mass of living organisms, measured in a specific area over a set time period

Why does an increased rate of photosynthesis not necessarily result in an increase of the same rate in biomass produced

Not all of the glucose produced in photosynthesis is stored in the plant (as starch or sucrose) which increases biomass, or used for growth. Some is used in respiration, to release energy for metabolic processes such as active transport.

Why might we want plants (not just to look pretty)

As a source of food, to release oxygen, and to absorb carbon dioxide

Method for observing pollen grains

Use a microscope. Place the pollen grains on a microscope slide, stain them with a dye, and place a coverslip over the slide (to prevent the samples from drying out).

Importance of cell differentiation

This allows stem cells to become specialised cells, so that they can form tissues and organs (e.g. the heart)

Reaction of roots to light

They show negative phototropism - they grow away from the light

Size difference between RBCs and WBCs

RBCs are smaller

Factor relating to the particles themselves (that cannot be changed) that affects rate of diffusion

Size - smaller particles will diffuse faster

What can diffusion do that active transport cannot

Diffusion can take place in non-living systems

Why might a strawberry field need more fungicide than a cereal field

Fruits are more prone to saprotrophic decay

Why are antibodies in milk useful for babies

They prevent infection by specific pathogens and provide immunity.

The uses of lipid

• Insulation or protection around organs

• Used in respiration as a source of energy

• Used as a store of energy

Causes of variation in offspring (5)

• Meiosis

• Mutations in DNA

• Environmental factors

• Random mating

• Random fertilisation

How do you use a variegated leaf to show chlorophyll is needed for photosynthesis - first step

Draw the pattern of chlorophyll (the green parts of the leaf)

Why do very high temperatures reduce growth of plants

• More transpiration, so more water loss

• Which leads to wilting, and the stomata close to prevent further loss

• Which means that there is less uptake of carbon dioxide in the plant

• So less photosynthesis

• The enzymes are denatured which also means less photosynthesis

Consequences of a diet too high in fat

• Obesity

• Blockage of arteries (as there is a build-up of plaque in the walls of arteries)

• Leading to coronary heart disease

• High blood pressure

• Diabetes

• Joint damage

• Gall stones

Improve: heat is radiated

Heat loss by radiation

Why does grass in a food web contain energy

Photosynthesis converts light energy into chemical energy, in the form of glucose

Why might the average height for some males be higher than females

• Genes on the Y chromosome are different to on the X

• Difference in diet

• Different metabolic rates

• Hormones

How can you tell if a disease is hereditary or not

• Look at family history

• Was the patient born with the condition

• Carry out a DNA test

Why can plants not absorb all light energy that reaches them from the sun

Some of the light is reflected, and some light falls on flowers

Why is the composition of air in the alveoli different from exhaled air

• Exhaled air is a mixture of inhaled air and alveolar air

• No gas exchange occurs in trachea

• As it only occurs at the alveoli

Osmoregulation definition

The control of the water and salt balance in the body

What is a partially permeable membrane

A membrane that allows water to pass through, but does not allow charged particles to pass through

Biodiversity definition

A measure of the variation shown by organisms in an ecosystem, based on the number and abundance of different species

Two reasons why many eggs are needed for cloning to be successful

Not all embryos implant in the uterus of the surrogate mother, not all eggs survive

Apart from sterilises-kills other bacteria-reduces competition, why is steam used to clean an industrial fermenter

It reduces contamination, and steam leaves no residue, only water

Why can stem cells repair a damaged heart

They can differentiate into any type of specialised cell, then can divide by mitosis to form tissues

Why is protein in urine an indicator of high blood pressure and kidney damage

Proteins normally do not pass through the basement membrane into the Bowman’s capsule, as they are too large. High blood pressure will force the protein molecules out, which results in damage to the glomerulus.

How does the temperature recorder do its thing in a fermenter

The temperature recorder detects changes in the temperature of the solution in the fermenter, and controls the water in the cooling jacket to maintain the optimum temperature for enzymes. If the temperature is too low, there is no water in the cooling jacket; if it is too high, cold water is released into the cooling jacket, to lower the temperature to prevent enzymes from denaturing.

Function of vitamin C

Forming skin and connective tissues

Impacts of excess energy/carbohydrate in the diet

Obesity and diabetes

Negatives of cloning animals

Genetically identical so reduced genetic variation in population, meaning it is more vulnerable to disease. Shorter lifespan

Why might producers have lower biomass than primary consumers

Producers are being continually consumed