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IGCSE Biology > Perguntas que eu errei > Flashcards

Perguntas que eu errei Flashcards

(ignora o resto)

1
Q

Suggest why a protective substance is necessary in the intestines. (2)

A
  • protect the intestine from pathogens
  • physical damage by food passing through intestine
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2
Q

What is the ileum?

A

an organ

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3
Q

Define the term chromosome. (2)

A

strand of DNA (1) that contains genetic material (2)

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4
Q

Describe the roles of FSH and LH in the menstrual cycle. (4)

A
  • FSH stimulates, development and maturation of follicles
  • FSH stimulates, development and maturation of an egg
  • FSH stimulates release of oestrogen from ovary
  • LH stimulates ovulation
  • LH stimulates release of progesterone (corpus luteum)
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5
Q

Describe the changes that occur in the lining of the uterus during one menstrual cycle. (3)

A
  • loss of lining at the beginning of the cycle
  • thickening of lining after loss, 2nd week
  • last 2 weeks, after ovulation: thickness of lining remains constant
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6
Q

Outline how the hormones in contraceptives act as a method of birth control. (3) (mari nao precisa saber disso, saiu do syllabus)

A
  • contraceptives contain progesterone
  • prevents release of FSH/LH
  • prevents, development of follicles
  • prevents ovulation
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7
Q

Function of effectors. (1)

A

carry out response

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8
Q

Function of receptors. (1)

A

detects the stimulus

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9
Q

Which organ produces bile? (1)

A

liver

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10
Q

Describe graph for enzyme activity x temp.

A

decrease after optimum is steeper than increase
line meets x axis at end

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11
Q

Explain the effect of a lack of magnesium ions of the colour of plant leaves. (2)

A

yellow (1) since magnesium is required for making chlorophyll (2)

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12
Q

Explain why the sequence of amino acids is important in the production of receptor molecules for neurotransmitters. (2)

A
  • the sequence of amino acids determines the shape of the protein
  • a complementary shape required for the receptor molecule to bind to neurotransmitter
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13
Q

Describe how artificial selection differs from natural selection. (3)

A
  • humans choose desired features
  • humans choose individuals to reproduce
  • selection not influenced by environment
  • decreases genetic variation
  • faster
  • for economic reasons
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14
Q

State two other sources, besides mutation, for genetic variation in populations. (2)

A

meiosis/crossbreeding
random fertilisation

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15
Q

Explain why vitamin D is important for the nutrition of children. (3)

A
  • needed for development of bones
  • needed for development of teeth
  • prevents rickets
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16
Q

Define the term ‘transmissible disease’. (2)

A

disease is caused by a pathogen (1) which is passed from one host to another (2)

17
Q

Explain why women should be vaccinated against rubella before they reach reproductive age. (4)

A
  • rubella is caused by a virus
  • virus can cross the placenta
  • and can affect embryo fetus
  • can cause serious damage to baby
  • vaccination stimulates long-lasting active immunity in mother, so immunity is gained before they become pregnant (2)
18
Q

Explain why the rate of photosynthesis will decrease if the humidity in the apparatus becomes very low. (3)

A
  • air becomes dry
  • diffusion gradient for water vapour increases
  • increased rate of transpiration
  • stomata close
  • CO2 cannot enter
19
Q

Explain why the rate at which CO2 is used in photosynthesis is greater than the rate of its uptake. (2)

A
  • carbon dioxide produced in respiration
  • plants respire all the time
  • carbon dioxide released by cells is used in photosynthesis
20
Q

Discuss the advantages of growing crops in glasshouses. (6)

A
  • glasshouses can maintain optimum conditions for
    photosynthesis
  • maintain optimum light intensity
  • by using artificial lights
  • maintain optimum temperature
  • heater/cooling
  • can use CO2 enrichment
    by burning fuels
  • supply of nutrients and minerals
  • herbicides not required
  • control of pollinators for selective breeding
21
Q

Outline the process of artificial insemination (3).

A
  • collect semen
  • selecting of sperm
  • determine when female is about to ovulate
  • insert sperm into female
22
Q

State two main features of fungal cells that are used to distinguish them from cells of prokaryotes. (2)

A
  • nucleus
  • mitochondria
23
Q

List 2 nutrients that need to be added to a fermenter to produce penicillin. (2)

A
  • water
  • glucose
  • amino acids
24
Q

Explain why the nutrients are sterilised before they are added to the fermenter. (1)

A

to make sure no other microogranisms can grow

25
Q

Explain why the fermenter has a gas outflow pipe. (2)

A

so that waste gases like CO2, produced during fermentation and respiration, can escape
reduce pressure

26
Q

Describe how acid rain destroys forests. (3)

A
  • acidifies soil
  • acidified soil causes leaching
  • damage leaves
  • affects ability of roots to absorb mineral ions
27
Q

Mutations are always inherited in single-celled organisms that reproduce asexually but are not always inherited in organisms that reproduce sexually. Explain why. (4)

A
  • mutations are found in the DNA
  • asexual reproduction offspring are genetically identical to the parent
  • so any existing mutations in parent DNA will be inherited
  • sexual reproduction involves two parents
  • mutation will only be in some of the gametes
  • meiosis does not result in genetically identical cells
28
Q

Suggest why amphibians are vulnerable to pollutants such as acid rain. (2)

A
  • permeable skin
  • they have fragile/thin gills
  • part of their life only exists in water
29
Q

Describe the structure of a villus and its role in the alimentary canal. (6)

A
  • lacteals absorb fatty acids and glycerol
  • lymphatic vessel, returns fats to blood
  • epithelial cell has microvilli
  • increasing the surface area for absorption
  • epithelial layer one cell thick for short diffusion distance
  • epithelial layer is where break down of maltose into glucose occurs
30
Q

Discuss the possible disadvantages of people changing the genes in a plant. (3)

A
  • cross-pollinate into wild populations
  • expensive GM seeds
  • ethical concerns
  • reduced natural biodiversity
31
Q

Predict and explain the effect of high humidity on the stomata. (3)

A
  • stomata will take longer to close
  • reduced water vapour concentration gradient
  • so the guard cells do not lose water as quickly
  • guard cells stay turgid
32
Q

State two types of cell membrane proteins. (2)

A

carriers
enzyme/maltase

33
Q

Explain how bacteria become resistant to antibiotics. (5)

A
  • random mutations in some bacteria
  • bacteria with resistance survive and reproduce
  • passing on their resistant gene
  • increase in frequency of resistant gene in population
  • natural selection/becoming better adapted for new environment

IGCSE Biology (28 decks)

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