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Biology Flash Cards > Unit 7 > Flashcards

Unit 7 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define Phenotype (2)

A
  1. Expression of genetic constitution of an organism
  2. And its interaction with the enviroment
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2
Q

Define Genotype (1)

A
  1. The genetic constitution of an organism
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3
Q

If a gene is sex-linked on the X chromosome, why is the phenotype more common in XY organisms? (2)

A
  1. Males have one allele
  2. Females need two recessive alleles
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4
Q

Mutation is one cause of genetic variation in
organisms.
Give two other causes of genetic variation.(2

A
  1. Crossing over
  2. Independent segregation
  3. Causes random fertilisation
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5
Q

In genetic crosses, the observed phenotypic ratios obtained in the offspring are often not the same as the expected ratios.
Suggest two reasons why. (2)

A
  1. Small sample size
  2. Fusion of gametes is random
  3. Linked Genes
  4. Epistasis
  5. Lethal Genotypes
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5
Q

Name the relationship between two alleles when both alleles appear in the phenotype (1)

A

Co-Dominance

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6
Q

Name the relationship between the two alleles when both alleles appear in the phenotype (1)

A

Epistasis

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7
Q

Explain what it means when two genes are linked (1)

A

On the Same chromosome

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8
Q

Which statistical test could the scientist use to
determine whether his observed results were
significantly different from the expected results?
Give the reason for your choice of statistical test.
(2)

A
  1. Chi Squared Test
  2. Categorical Test
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9
Q

Define Gene Pool (1)

A

All alleles in a population

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10
Q

Define species (1)

A

Organisms that can breed together and produce fertile offspring

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11
Q

The conditions under which the
Hardy-Weinberg Principle
applies (5)

A
  1. No mutations
  2. Random mating
  3. Large Population
  4. Isolated Population
  5. No selection pressure
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12
Q

What are the two equations used in the Hardy-Weinberg equation? (2)

A
  1. P + Q = 2
  2. P2 + Q2 = 2PQ = 1
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13
Q

Describe Allopatric Speciation (5)

A
  1. Geographical Isolation
  2. Reproductive separation
  3. Different selection pressures
  4. Variation due to mutations
  5. Different alleles passed on
  6. Eventually different species cannot interbreed to produce fertile offspring
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14
Q

Why does speciation take a long time? (3)

A
  1. Initially few animals with favourable allele
  2. Individuals with allele will have more offspring
  3. Takes many generations for favourable mutation to become the most common allele
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15
Q

Natural Selection in Resistant Strains (5)

A
  1. Some individuals in population are naturally resistant
  2. Due to mutation
  3. These survive when non-resistant are killed
  4. To reproduce and pass on the allele for resistance
  5. Increase in frequency of allele for resistance
16
Q

Describe sympatric speciation (4)

A
  1. Not Geographically isolated
  2. Mutation causes reproductive isolation
  3. Gene pools kept separate
  4. Different alleles are passed on
  5. Cannot breed to produce fertile offspring
17
Q

Define Community (1)

A

All groups of populations living and interacting with each other in an area

18
Q

Assumptions with Mark, Release and Recapture (5)

A
  1. No Immigration
  2. No losses to predation
  3. Marking does not affect survival
  4. Birth rate and Death rate equal
  5. All belongs to one population
19
Q

Outline method of Mark, Release and Recapture (4)

A
  1. Capture sample, mark then release
  2. Ensure marking isn’t harmful to survival
  3. Allow time for organism to randomly distribute before collecting a second sample
  4.  (Population =) number in first sample × number in second sample divided by number of marked fish in second sample/number recaptured
20
Q

Describe how you could estimate the size of a population using random sampling (4)

A
  1. Use a grid
  2. Method of obtaining random numbers, example random number generator
  3. Count number in a quadrat
  4. Large sample and calculate the mean
  5. Valid method of calculating total number of plants, example mean number of plants per quadrat
21
Q

Why repeat/large sample size? (1)

A

So representative

22
Q

Why random? (1)

A

Avoid bias

23
Q

The scientist used percentage cover rather
than frequency to record the abundance of
algae present. Suggest why. (1)

A

Too many to accurately count

24
Q

Describe use of systematic sample to count plants (5)

A
  1. Systemic sampling at regular intervals along transect line
  2. Transect the line from measurement told
  3. Count number in a quadrat
  4. Large sample and calculate mean
25
Q

Effect of increased plant/animal diversity on ecosystem (3)

A
  1. Increase in plant diversity leads to more different types of food for animals
  2. Increase in variety of animals leads to increase in predator species
  3. Increases in more different niche
26
Q

Define Niche (3)

A
  1. Niche is the role that a species plays in within a community
  2. Includes food resources
  3. No two species can occupy identical niche
27
Q

Predator-Prey Relationship (4)

A
  1. As pest numbers increase, more predators, so they increase
  2. Increased predation of pests reduces numbers
  3. Low number of pests results in less food for predators so their numbers decrease
  4. Low predator numbers allow pest population to rise
28
Q

Describe Succession (5)

A
  1. Colonisation by pioneer species
  2. Pioneers change the environment
  3. Changes make the environment less hostile for new species
  4. Increase in Diversity
  5. To climax community
29
Q

Describe Competition in Succession (3)

A
  1. Pioneer species increases then decreases
  2. Principle of a species makes the conditions
  3. New species are better competitor so pioneer species outcompeted
30
Q

Give two features of a climax community (3)

A
  1. Same species present over long time
  2. Abiotic Factors are constant over time
  3. Populations are stable
31
Q

Suggest one reason for conserving woodlands (1)

A
  1. Conserving habitats
  2. Protecting endangered species
  3. Reduces global warming
  4. Source of medicines
  5. Reduces Erosion
32
Q

Succession occurs in natural ecosystems. Describe and explain how succession occurs (4)

A
  1. Colonisation by pioneer species
  2. Pioneer species change the environment
  3. Makes the environment less hostile for new species
  4. Increase in diversity/biodiversity

Biology Flash Cards (8 decks)

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