Biology GCSE paper 2 missed questions

What are the three features of a binomial name?

Genus, species, uppercase first letter of genus

What are three abiotic factors affecting plant growth

• Light intensity

• Temperature

• Moisture level

• Soil pH content

• Soil mineral content

• Wind intensity/direction

• Carbon dioxide levels

What is geotropism? [2]

Growth response due to gravity

How does a plant’s response to light help it survive? [3]

The leaves absorb more light, so more photosynthesis, producing more glucose

What are the three stages of genetic engineering?

1. Useful gene isolated from genome using enzymes

2. Gene iserted into vector using ezymes (cut virus or bacterial plasmid)

3. Gene containing vector introduced into target organism

Which part of the body monitors water content of the blood?

The brain

Which part of the body releases the hormone controlling water loss from the body?

The pituitary gland

What are two biological reasons why a kidney transplant is better than dialysis?

• Changes in concentrations of substances minimised with a kidney transplant so less chance of body cell damage

• Kidney transplant isn’t repeatedly puncturing skin, reducing chance of infection

Why does asexual reproduction produce genetically identical offspring?

Only uses mitosis so all cells recieve a copy of every gene

Why are offspring produced with flowers, fruits and seeds not genetically identical? [3]

Unique gametes are produced by meiosis and fused with another parent’s gametes, creating genetic variation

Why does asexual reproduction require less energy than sexual?

No need to produce gametes

What are two advantages of sexual reproduction for survival in plants?

• New combinations of alleles gives genetic variation

• Seeds dispersed to new area so less vulnerable to habitat loss or competition with offspring/parent

• Larger number of offspring produced rapidly increases population

What is the difference between a volunatry reaction and reflex?

A voluntary action reuquires concious thought and is therefore coordinated by the brain, whereas a reflex is an involuntary action coordinated by the spinal cord

How could one base changing stop an enzymes function? [4]

Gives different 3 base set, coding for a different amino acid, altering the active site so substrate no longer fits

What is a mutation?

A change in DNA

Which two scientists suggested the theory of evloution by natural selection

Alfred Wallace and Charles Darwin

Why does a low pH prevent decay?

Low pH denatures enzymes so less energy released in decomposers

What percent of biomass is transferred between trophic levels in a stable community?

~10%

What do DNA strands consist of? [3]

Nucleotides consisting of a sugar and phosphate group with one of four bases attatched to the sugar

How does using peat as fuel harm the environment? [4]

Temperature increases because carbon dioxide is released from decomposing peat bog becoming exposed to oxygen and is produced by burning peat. Additionally, methane is released from the peat bog

What hormone is produced by the thyroid?

Thyroxine

Define homeostasis

The regulation of internal conditions for optimum enzyme activity

How does reducing competition help a plant grow?

• Less competition for space

• More light/water for photosyntehsis so more glucose produced

• More glucose for energy

• More water for transport

• More magnesium for chlorphyll

• More nitrate for amino acids

• More phosphate for DNA

Give three ways coordination by the endocrine system is different from coordination by the nervous system.

• Endocrine is slower

• Endocrone is longer-lasting

• Endocrine transmits signals via hormones in blood instead of electrical signals via neurones

How does the body respond when blood glucose levels are too high? [3]

Insulin secreted by pancreas into bloodstream, causing glucose to move from blood into liver and muscle cells where excess is converted into glycogen for storage.

How does the body increase the blood glucose concentration? [3]

Glucagon is secreted by the pancreas into the bloodstream, causing the liver to turn glycogen into glucose, releasing it into the blood

What are filtration and selective reabsorption in the kidneys?

Filtration is when substances are filtered out of the blood as it passes through the kidneys. Selective reabsorption is when useful substances like glucose, some ions and the right amount of water are absorbed back into the blood.

Name three substances removed in urine.

Urea, excess water, excess ions

Why must blood ion content be regulated? [2]

If wrong, the too much or too little water is drawn into cells via osmosis which can daamage cells or impair function.

What are the two main functions of testosterone and of oestrogen?

Testosterone - triggers development of secondary s*xual characteristics and stimulates sperm production

Oestrogen - triggers development of secondary s*xual characteristic and part of the menstrual cycle

How do progesterone and oestrogen function as contraception? [2]

Both inhibit FSH production so no eggs mature, progesterone inhibits LH preventing egg release

What three types of hormonal contraception contain slow-release progesterone?

Injection, skin patch, implant

What are the two barrier methods of contraception?

Condoms and diaphragms

How do IUDs, spermicidal agents and abstaining work?

IUDs - prevent implantation of an embryo or release a hormone

Spermicidle agents - kill or disable sperm

Abstaining - avoid s*x when egg is in oviduct, preventing fertilisation

What are the three stages of IVF?

1. Mother given FSH and LH to stimulate maturation of several eggs

2. Eggs collected from mother and fertilised by father’s sperm in laboratory

3. Fertilised eggs develop into embryos

4. Once tiny balls of cells, one or two embryos are inserted into mother’s womb

How do roots grow downwards?

When root grows sideways, gravity causes auxin to diffuse to lower side, inhibiting its growth so top cells elongate faster, bending root downwards.

What three ways are auxins used commercially?

• In selective weedkillers

• In rooting powder to grow plants from cuttings

• In growth medium to stimulate cells from a plant to divide

Describe how hormones are used to make sure fruit sold in stores are ripe. [3]

Fruit are picked while unripe and ethene gas which stimulates enzymes that cause the fruit to ripenis added on the way to stores, speeding up their ripening

What is the optimum body temperature

37℃

What do genes do?

Code for a specific amino acid sequence, put together to make a specific protein

What is a genome

The entire set of genetic material in an organism

What are three ways understanding of the human genome is used?

• Identifying genes responsible for different diseases

• Understanding and developing treatments for inherited diseases

• Understanding migration of human ancestors

What is an example of what non-coding DNA cdan do?

Can switch genes on and off to control wether a gene is expressed

How does a newly assembled chain of amino acids become a protein with a specific function?

Folds into a unique shape, allowing it to perform its function

Give three examples of types of proteins with different functions

• Enzymes - catalyse biological reactions

• Hormones - chemical messangers

• Collagen - strengthens connective tissue

What is a mutation?

A random change in DNA

Explain the three types of mutation

• Insertions - new base inserted, causing a knock-on effect on amino acids coded further down the sequence

• Deletions - a random base is deleted, causing a knock-on effect on amino acids coded further down the sequence

• Substitutions - a random base is changed to a different one

What is s*xual reproduction?

The fusion of male and female gametes, creating genetic variation in offspring

What is asexual reproduction?

Reproduction involing only one parent, leading to genetically identical offspring.

List the main steps in meiosis

1. Genetic information is duplicated, forming two-armed chromosomes arranged in pairs

2. Pairs are pulled apart and cells divide, each with one copy of each chromosome

3. Chromosomes line up again, arms pulled apart

4. Each cell divides in two, so each has only one single set of chromosomes

What are two reasons why each gamete is genetically different from the others?

• Chromosomes shuffled during meiosis

• Each only gets half of the chromosomes at random

Give three examples of organisms that use asexual and sexual reproduction and how.

• malarial parasites reproduce asexually in human host but sexually in mosquito

• Fungi reproduce asexually by spores but also sexually to give variation

• Plants produce seeds sexually but some produce runners or bulbs asexually

How many pairs of chromosomes are there in ordinary human body cells?

23

What are the sex chromosomes in males and in females?

• Males - XY

• Females - XX

Name two characteristics that are controlled by single genes.

Mouse fur colour and red‑green colour blindness

What did mendel conclude from his observations of pea plants? [4]

• Characteristics are determined by ‘hereditary units’ which are passed onto offspring unchanged, one from each parent. Can be dominant or recessive, dominant characteristic expressed if individual has both

Give three developments in genetics that showed the importance of Mendel’s discoveries.

• Late 1800s — scientists observe how chromosomes behave during cell division.

• Early 20th century — scientists notice chromosomes and ‘hereditary units’ behave similarly and suggest that the ‘hereditary units’ are found on chromosomes - genes

• 1953 — the structure of DNA is determined and scientists find out how genes work