Common q

Question 1

Define sensitivity.

Answer 1

the ability to detect and respond to changes in the internal or external environment

Question 2

Define growth

Answer 2

a permanent increase in size and dry mass

Question 3

How bacteria differ from other from other groups of organisms?

Answer 3

no nucleus (circular loop of DNA)
no mitochondria or chloroplast
celll wall of peptidoglycan

Question 4

State the function of nucleus.

Answer 4

stores genetic information

controls the activity of the cell

controls how cells divide

stores instructions for, protein synthesis

Question 5

State the function of cell membrane.

Answer 5

controls what goes in and out of the cell

separates the contents of the cell with its environment

Question 6

Explain what happens to the cell of a leaf cause wilting.

Answer 6

Rely on water for support. Plant may lose more water from its leaves that it takes up from its roots. Turgor pressure caused by water pushing outwards on the cell wall of plant cells decreases. Individual cells lose so much water that they become soft and floppy, flaccid.

Tissues in the leaves are no longer supported by turgid cells pushing outwards against one another. The leaves become soft and floppy, flaccid.

Question 7

What happens during plasmolysis?

Answer 7

cell membrane tears away from the cell wall, can kill a plant cell because cell membrane is damaged as it tears away

Question 8

State features of diffusion that do not apply to active transport.

Answer 8

no energy ;
substances move down a concentration gradient ;
does not have to occur across a membrane ;
no protein carriers

Question 9

What is the benefit of having more fiber in diet?

Answer 9

stimulates peristalsis more than soft foods, less risk of constipation

Question 10

Describe the use of amino acids in plants.

Answer 10

used to make proteins for growth

Question 11

Explain how gravitropism enables a plant to survive

Answer 11

anchors plant, absorbs water and minerals between soil particles, to reach light, access to pollinators such as bees

Question 12

What are the symptoms of anaemia.

Answer 12

not enough red blood cells so tissues do not get enough oxygen delivered to them

Question 13

Describe the effects of diarrhoea on the body. (Cholera)

Answer 13

large quantities of water is lost from the body in watery faeces, death may occur without treatment due to dehydration and loss of chloride ions in the blood

Question 14

Explain why vitamin D is important?

Answer 14

helps calcium to be absorbed for making bones and teeth, prevents rickets

Question 15

Explain why iron is important?

Answer 15

for making haemoglobin, the red pigment in blood which carries oxygen, prevents anemia

Question 16

Explain why vitamin C is important?

Answer 16

to make stretchy protein, collagen, found in skin and other tissues, keeps tissues in good repair

Question 17

Describe the effects of vitamin D deficiency in humans.

Answer 17

rickets: bones become soft and deformed

Question 18

Define chemical digestion.

Answer 18

breakdown of large insoluble molecules in food into small soluble molecules, so that they can be absorbed

Question 19

Define the term assimilation.

Answer 19

the uptake and use of nutrients in cells

Question 20

What is the function of canine?

Answer 20

piercing food and
killing prey (in carnivores)

Question 21

What is the function of molar?

Answer 21

grind food to increase their surface area

Question 22

Explain how villi are adapted for absorption.

Answer 22

microvilli provide a large surface area ;
epithelium, one cell thick  to diffuse easily ;
ref. to enzyme production ;
good blood supply to maintain a steep concentration gradient ;
ref. to lacteal and fat transport ;

Question 23

Suggest why a protective substance (mucus) is necessary in the intestines.

Answer 23

help food slide easily through, prevent self-digestion

Question 24

What are nerve impulses?

Answer 24

an electrical signal that passes rapidly along an axon

Question 25

Explain the advantages of coordinating the response to a dangerous situation
using both the nervous system and the endocrine system.

Answer 25

Nervous system responds rapidly. Impulses travel to effectors.

Effects of endocrine system lasts long. Hormones travel around the body and allows target organs to respond.

Less energy required since having to have nerves send impulses throughout tissues. More effective response due to using two systems.

Question 26

Describe the role of insulin in the body.

Answer 26

Insulin is a hormone secreted by the islets on the pancreas which decreases blood glucose concentration.

Islets detect increase in glucose concentration and secrete insulin. This is an example of homeostasis.

Insulin reaches the liver causing the liver to absorb glucose from the blood. Some is used for respiration, but some is converted to glycogen which is then stored in the liver.

Question 27

Explain how co-ordination by hormones differs from co-ordination by nerves.

Answer 27

-made up of neurones
-information transmitted in the form of electrical impulses
-impulses carried along neurones
-impulses travel quickly so action is fast
-effect of impulse lasts a short time

Question 28

State ways in which a voluntary action differs from an involuntary action

Answer 28

slower, think about actions, not automatic, learnt action, response to stimulus is not always the same

Question 29

Describe and explain the changes that occur in the eye when adjusting focus
from a distant object to a near object

Answer 29

ciliary muscles contract ;
suspensory ligaments become slack;
lens becomes fatter;
causing more refraction

Question 30

Outline the role of liver in excretion

Answer 30

1. Digestive enzymes in the stomach, duodenum and ileum break down proteins.
2. Amino acids are absorbed into the blood capillaries in the villi in the ileum.
3. Capillaries join up to form the hepatic portal vein which takes the amino acids to the liver.
4. Liver allows some to carry on in the blood, but excess (more than required) is removed from the body.
5. Enzymes in the liver split up each amino acid molecule.
6. The energy-containing part is kept and turned into carb and stored. The nitrogen-containing part is turned into urea.
7. Urea dissolves in the blood plasma and is taken to the kidneys to be excreted
8. This process is called deamination!

Question 31

What do the kidneys remove?

Answer 31

excess water, excess ions, excess glucose and urea

Question 32

What is deamination?

Answer 32

the removal of the nitrogen-containing part of amino acids to form urea

Question 33

If too much urea builds up in the blood..

Answer 33

you would get very ill, its toxic to the body

Question 34

Outline the structure of a kidney.

Answer 34

Tissue making up the outer layer, cortex. Tissue making up the inner layer, medulla. Made up of thousands of nephrons. Each begins in the cortex (out and in, out and in). Nephrons join up with the ureter.

Renal artery divides to form many tiny, coiled capillaries called glomeruli.

Question 35

Describe the formation of urine.

Answer 35

Blood flows to kidney in renal artery, which divides to form many tiny, coiled glomeruli. Blood is filtered here. Only small molecules can pass through the filter, but large molecules and blood cells cannot. Filtrate: water, urea, glucose, ions. These move into the nephron.

All of the glucose, most of the water and some of the ions are taken back into the blood as the fluid flows through nephron.
Reabsorption. Blood capillaries come close to the nephron making it easy to move back.

Question 36

What is the advantage to red blood cells of not having a nucleus?

Answer 36

more space for packing in millions of molecules of haemoglobin, able to carry more oxygen

small so can squeeze through the tiniest capillaries

biconcave, small volume great sa, speeds up diffusion rate of oxygen in and out rbc

Question 37

Blood glucose concentration too high?

Answer 37

Liver cells break down glycogen to glucose and release it into the blood.

Question 38

What is negative feedback?

Answer 38

a mechanism that detects a move away from the set point, and brings about actions that take the value back towards the set point

Question 39

What is a set point?

Answer 39

the normal value or range for a particular parameter; eg: normal range of blood glucose concentration or the normal body temperature

Question 40

What is type 1 diabetes?

Answer 40

a condition in which insufficient insulin is secreted by the pancreas, so blood glucose concentration is not controlled

High: dry mouth, blurred vision, very thristy, h rate and b rate may increase

Low: confusion, irrational behaviour, become unconcious

Question 41

What damage can type 1 diabetes cause?

Answer 41

Over long periods of time, it can damage organs.

Question 42

What do people with diabetes do regularly? (Testing)

Answer 42

Habit of checking their blood glucose concentration using a simple sensor.
Can test their urine for glucose using a dipstick. (Should not contain glucose, but if its high..)

Inject with insulin (different types) Type 1 will take rapid-acting insulin just before or after they eat a meal. Adjust dose accordingly. Long-acting insulin taken daily at the same time, provides background dose of insulin.

Question 43

What else can people with diabetes do?

Answer 43

Eat little and often. Avoiding large amounts of carbs.

Question 44

Define asexual reproduction.

Answer 44

a process resulting in the production of genetically identical offspring from one parent

Question 45

Define sexual reproduction.

Answer 45

a process involving the fusion of nuclei of two gametes (this is callled fertilisation) to form a zygote and production of offspring that are genetically different from each other

Question 46

Explain why the sex of a child is determined by its father

Answer 46

sex is determined by X and Y chromosomes, females can only provide X chromosome, only males can provide the Y chromosome ;

Question 47

Outline the role of LH

Answer 47

Causes ovulation.

Question 48

Describe what happens at ovulation

Answer 48

an egg is released from the ovary into the oviduct.

Question 49

Explain the advantages of presenting information about food webs as a pyramid of biomass and not as a pyramid of numbers.

Answer 49

Take the size of each organism into account

Question 50

Explain the advantages of presenting information about food webs as a pyramid of energy and not as a pyramid of biomass.

Answer 50

shows actual energy transfer ;
time is taken into account ;
more accurate ;

Question 51

How do fungus reproduce?

Answer 51

Fungus forms spores, which are tiny groups of cells with a tough, protective outer covering. The spores can be spread by wind or animals, and grow into a new fungus.

Question 52

Explain how selective breeding/ artificial selection differs form natural selection.

Answer 52

Natural:
- environment which determines which individuals survive and breed
- random mating; animals choose mates, plants receive pollen from any anthers, onto any stigmas
- adaptive features increase chances of an individual surviving
- only slightly better chance of some individuals surviving because they have a particular feature, individuals that do not have the feature still have a chance to reproduce
- genetic variation is greater
- speed of change in a population is slow

Question 53

What are the features of gas exchange surfaces?

Answer 53

• thin to allow gases to diffuse across them quickly
• close to an efficient transport system to take gases to and from the exchange surface
• large sa, so that a lot of gas can diffuse across them at the same time
• have a good supply of oxygen

Question 54

How do ferns reproduce?

Answer 54

They reproduce by spores produced on the undersides of their fronds.

Question 55

State what is meant by haploid and diploid.

Answer 55

diploid- having two sets of chromosomes
haploid- having only a single set of chromosomes

Question 56

Diploid or haploid?

gametes
zygote

Answer 56

gametes are haploid, zygote is diploid

Question 57

State which events occur between pollination and fertilisation.

Answer 57

Pollen grain lands on right kind of stigma and pollen grain grows pollen tube which grows down the style
and ovary reaches the ovule. It secretes enzymes to digest a pathway through the style.

Ovule is surrounded by several protective layers of cells called integuments. At, one end, there is a small hole called a micropyle into the ovule. The pollen tube grows through the micropyle, into the ovule.

The pollen nucleus, male gamete, travels along the pollen tube into the ovule. Fuses with the ovule nucleus, female gamete and a zygote forms. One pollen grain can only fertilise one ovule. Fertilisation occurs in ovules.

Question 58

What is pollination?

Answer 58

the transfer of pollen grains from the male part of the plant (anther of stamen) to the female part od the plant (stigma)

Question 59

State which events occur between fertilisation and production of seed.

Answer 59

Sepals, petals and stamens wither and fall off. Ovules start to grow. Each ovule contains a zygote which was formed at fertilisation, and divides by mitosis to form an embryo plant. The ovule is now a seed.

Question 60

How does a seed remain dormant? (inactive with metabolic reactions taking place very slowly or not at all)

Answer 60

When a seed is formed, the water was drawn out of it. Without water, almost no metabolic reactions can take place inside it. A dormant seed can survive harsh conditions, such as cold and drought which would kill a growing plant.

Question 61

What conditions does a seed need to germinate?

Answer 61

water, oxygen, warm temperature, light is usually not neccessary (seeds in tropical rainforests will only germinate if there is light)

Question 62

Compare self-pollination and cross-pollination.

Answer 62

self-pollination have some variation, cross-pollination has more variation (new combos of genes are formed)

Question 63

How do potatoes reproduce?

Answer 63

When it is warm enough, some plant stems grow normally and produce leaves above the ground. Other stems grow under the soil. Swellings, called tubers, form on the stems.

Sucrose is translocated from the leaves to the underground stem tubers, where it is converted to starch and stored. They grow larger and larger. Many stem tubers from one plant.

Question 64

Tubers are harvested..

Answer 64

Used as food, but some saved to produce crop. Tubers planted underground. Many tubers= rise to many plants. Tubers can be cut into several pieces to get even more plants. As long as there’s a bud.