Biology Paper 1 focus topics

Despite the title, it does include paper two as well. Don't be fooled!

describe the role of the vacuole in plant cells

a large sac in the middle of the cell that contains a watery solution of sugars and salts (cell sap). It helps maintain the structure and shape of the cell.

describe the role of the cell wall in plant cells

-made of cellulose, strong

-allows it to maintain the shape of the cell

-also found in algae

describe the role of the cell membrane

-controls the movement of substance in and out of the cell

carbohydrase e.g. amylase: site of production, action, word equation and use of products

-produced in the salivary gland, pancreas and small intestine

-acts in the mouth and small intestine

-carbohydrates --> simple sugars e.g. starch into glucose

-used to build new carbs, in storage (glycogen - short term, fat - long term) and for respiration

protease: site of production, action, word equation and use of products

-produced in the stomach, pancreas and small intestine

-acts in the stomach and small intestine

-proteins --> amino acids

-build new proteins for growth and repair

lipase: site of production, action, word equation and use of products

-produced in the pancreass

-acts in the small intestine

-lipids --> glycerol and fatty acids

-build new lipids for storage

describe the function of bile

-made in the liver, stored in the gallbladder

-increases rate of fat breakdown by lipase: it is alkaline to neutralize hydrochloric acid from the stomach to maintain optimum ph for enzymes

-emulsifies fat drops to from small droplets, increasing surface area for enzymes to work on

describe how the small intestine is adapted for efficient absorption

-many capillaries - good blood supply to maintain high concentration gradient needed for quick diffusion/active transport

-villi and microvilli provide a large surface area

-villi and capillary wall are thin, only one cell thick for a shorter diffusion distance

-small intestine is very long, increasing absorption time

cells have many mitochondria for aerobic respiration to release energy needed for active transport

Describe the method of the required practical to investigate the effect of pH on the rate of reaction of amylase enzyme

1. put 2cm^3 of starch solution into a boiling tube

2. put 2cm^3 of amylase solution and 2cm^3 buffer solution at pH 5 into a second boiling tube

3. put both boiling rubes into a water bath at 35 degrees

4. after 5 mins, mix the amylase and starch together in one boiling tube, keeping it at 35 degrees

5. after 30 seconds adda drop of the starch and amylase mixture to a drop of iodine solution in one well of a spotting tile

6. repeat step 5 until the iodine solution no longer changes colour

7. repeat steps 1-6 three timesusing buffers at pH 5, 6, 7, 8 and 9.

In the enzymes required practical, how can the data be analysed?

-rate = 1000/time taken for the reaction to end

-a graph should be plotted with the rate on the y axis against pH on the x axis

How can you evaluate the enzymes required practical?

-repeatability - good use of water bath to maintain the control variable of temperature

-precision - improve this by taking samples more frequently

-accuracy of optimum determined - improve this by repeating at smaller intervals of pH close to the current optimum pH

describe the blood cell adaptations

RBC:

-tiny to pass through narrow capillaries

-biconcave shape, gives a large surface area for fast oxygen diffusion

-no nucleus, allows more space for haemoglobin, increasing oxygen carrying capacity

WBC:

-flexible to move through capillary walls into tissue, and to change shape to engulf and digest pathogens

describe cytokinesis

the cell membrane AND cytoplasm splits (to form two genetically identical daughter cells)

how does e coli divide

binary fission

why could the rate of cell division slow down (plateau on a graph)

-a shortage of nutrients or oxygen can cause cells to die/the death rate becomes equal to the rate of cell division

describe a stem cell

-cells that are able to divide

• undifferentiated cells / not specialised

• can become other types of cells / tissues or become specialised /differentiated

Give an advantage of using one's own stem cells to treat a condition instead of using stem cells donated from another person

perfect tissue match or hard to find suitable donors

allow same/matching antigens

allow no danger of rejection

allow no need to take immunosuppressant drugs (for life)

ignore genetically identical or same DNA

Why would it not be possible to treat a genetic disorder in a child using his own umbilical cord stem cells?

stem cells have same faulty gene / allele / DNA / chromosomes

Suggest two reasons why using cultured meat may slow down the rate of global warming.

-fewer cows

-less methane released from cows

-less CO2 in the atmosphere because of less deforestation

Suggest two other possible advantages of producing cultured meat instead of farmed meat.

Do not refer to cost in your answer.

could be mass produced to feed an increasing population

• disease free meat

• no / low fat

• no harm to animals or less intensive farming

antibiotic free meat

• more land available for farming crops

Describe how mycoprotein is produced

Fusarium fungus is grown in fermenters

Glucose syrup provides energy for growth

Aerobic conditions ensure respiration

Ammonia is added as a nitrogen source for protein synthesis

Mycoprotein is harvested and purified for consumption

What is a dominant allele

allele expressed even when other allele present, or expressed if just one copy of allele is present, or expressed if heterozygous

Suggest why it is ethically more acceptable to take stem cells from an umbilical cord instead of using stem cells from an embryo

destroying/damaging (potential) human life

allow cord would have been discarded anyway

Explain why each chromosome must become two strands before the cell divides.

-one copy of each (chromosome / chromatid / strand) to each offspring cell

-each offspring cell receives a complete set of / the same genetic material

Describe the product and process of therapeutic cloning

-take stem cells from the patient's bone marrow or skin

-if needed, remove or change the faulty gene

-create an embryo using these stem cells

-remove stem cells from the embryo and stimulate them to divide and differentiate into the required type of cell

Describe the role of staining in mircoscopy

allows us to view colourless specimens and view highlight different structures or tissues

Distinguish between cell differentiation in animals and plants

Most types of animal cell differentiate at an early stage, whereas many types of plant cells retain the ability to differentiate throughout life.

Describe the process of cell differentiation

as a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function, becoming a specialised cell

explain the function of mitochondria

it is the site of aerobic respiration, (containing enzymes that carry out aerobic respiration), to release energy for the cell to use

describe the stages of the cell cycle, including mitosis

G1. cell growth and increase in the number of sub-cellular structures

S. DNA replicates to form two copies of each chromosome

G2. cell growth

M. mitosis: one set of each chromosome is pulled to each end of the cell, forming two nuclei, then cytokinesis

Explain how electron microscopy has increased understanding of sub-cellular structures

An electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures.

name the types of cells that have a cell wall made of cellulose

plants and algal cells

Evaluate the use of statins

-reduce cholesterol

-treat some cardiovascular diseases without surgery

-side effects such as liver damage

Explain how bacteria can make us feel ill

-reproduce rapidly inside the body, secreting toxins that damage tissues and cause symptoms (vomiting, diarrhoea)

Describe a benign tumour

-growths of abnormal cells contained within one area, usually within a membrane, do not invade other parts of the body

Why should bacterial cultures be incubated at 25°C in school labs

-to reduce the growth of pathogenic bacteria, that have optimum temperatures of 37°C

Define 'risk factor'

-an aspect of a person's lifestyle or a substance in a person's body or environment that are linked to an increased rate of a disease

Describe the pathogen, symptoms, spreading method, and preventative measures taken to reduce the spread of measles

-virus

-fever and red skin rash

-inhalation of droplets of sneezes and coughs

-most young children are vaccinated against measles

Describe how the skin acts as a non-specific defence system of the human body against pathogens

-skin is a tough, dead outer layer that acts as a physical barrier

-skin produces an oil called sebum that repels pathogens

-platelets are involved in forming clots and scab, that form over cuts to form a barrier

Describe how different types of disease may interact

-Defects in the immune system mean that an individual is more likely to suffer from infectious diseases

-viruses living in cells can be the trigger for cancers

-immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma

-prolonged severe physical ill health can lead to depression or other mental illnesses

Explain how vaccination will prevent illness in an individual

-involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies

-if the same pathogen re-enters the body the memory (lymphocyte) cells recognise the pathogen and respond quickly to produce the specific correct antibodies at a high concentration, preventing infection

How can damaged villi cause poor growth

-damaged villi reduce surface area for absorption of food molecules
-therefore fewer amino acids and glucose absorbed
-with less glucose transfer of energy from respiration is reduced
-and fewer amino acids available to build up new proteins

Describe the function of white blood cells

-produce antitoxins to neutralise toxins (produced by bacteria etc)
-engulf, digest and destroy pathogens (phagocytosis)
-produce antibodies that target pathogens

Explain fully why antibiotics cannot be used to treat viral infections

-viruses live inside cells
-viruses are inaccessible to antibiotic - antibiotic would have to kill cell

Explain why antibiotic resistance occurs

-non resistant strains killed by antibiotics leaving only resistant ones to multiply without competition
-overuse of antibiotics gives more chances for bacteria to develop resistance (by genetic mutations)

Explain a genetic mutation

-a mutation is a change in the base sequence of a gene (be specific to the figure/diagram if given)

-this changes the base sequence of the gene copy that leaves the nucleus for translation

-it changes the order of amino acids produced in the protein (or stop the protein from being made)

-it can change the shape of the protein (or active site of the enzyme)

-it can change the function of the protein