BY5

HideShow resource information
  • Created by: jawjeener
  • Created on: 22-03-16 10:43
What are the structures which produce spermatozoa?
Seminiferous tubules
1 of 74
What are two structures which produce secretions that aid sperm mobility?
Seminal vesicle // Prostate gland
2 of 74
Why is the middle piece of the sperm packed with mitochondria?
To provide ATP for movement
3 of 74
What is the function of the Sertoli cells?
To nourish the spermatids and protect them from the immune system
4 of 74
What is the function of the interstitial cells?
To secrete testosterone // The male hormone
5 of 74
What is meant by the term 'fertilisation'?
The fusion of the sperm with the ovum
6 of 74
What is the product of fertilisation?
Zygote
7 of 74
Why is internal fertilisation a necessary adaptation for life on land?
So that the organism becomes independent of water as the sperm is introduced directly into the female tract
8 of 74
What is the function of the enzymes released after the rupture of the acrosome membrane?
To soften the layer of cells surrounding the oocyte to enable to sperm to penetrate the egg
9 of 74
What is the function of the fertilisation membrane?
To prevent the entry of further sperm
10 of 74
Why is urine used to test for pregnancy?
Urine of a pregnant female contains the hormone hCG
11 of 74
What is one antigen?
hCG
12 of 74
Why does a blue band appear in the large window when a sample of urine from a pregnant woman is tested?
The antibody hGC forms a blue bead complex with the first antibody // This complex binds to the antibody in the large window and prevents it diffusing any further
13 of 74
What are three parts that make up a carpel?
Ovary // Style // Stigma
14 of 74
What is the difference between self-pollination and cross-pollination?
Self - the transfer of pollen to the stigma of the same flower // Cross - the transfer to another flower on another plant of the same species
15 of 74
Why do wind-pollinated flowers produce large quantities of pollen?
Due to chance, much of the pollen fails to reach the stigma of another flower and so it is wasted
16 of 74
What is one way in which pollen grain is adapted for dispersal?
A tough wall to prevent drying out // sculptured // spiky surface to attach to insects
17 of 74
What is the function of the pollen tube nucleus?
To control the growth of the pollen tube
18 of 74
What assists the growth of the pollen tube?
The secretion of enzyme to digest a path // May provide nutrients for growth
19 of 74
How is the triploid endosperm nucleus formed?
One of the male nuclei from the pollen tube fuses with both polar nulcei in the embryo sac
20 of 74
What is the definition of a 'recessive allele'?
It expresses itself only in the presence of another identical allele // The effect of the allele is apparent in the phenotype of the diploid organism only
21 of 74
What is meant by the phrase 'a gene is sex linked'?
A gene that is carried on either the X or the Y chromosome
22 of 74
What percentage of recombinants would you expect from a cross of linked genes?
5-10%
23 of 74
Why do gene mutations rarely show up in the phenotype?
Most mutations are recessive and the recessive allele is not expressed in the genotype
24 of 74
Why is bacteria used widely in mutation experiments?
Bacteria have a short life cycle and show a greater rate of mutation
25 of 74
What is one mutagen?
Xrays // Gamma radiation // UV light
26 of 74
What term is applied to a mutagen that causes cancer?
Carcinogen
27 of 74
What are the two forms of mutation?
Gene and chromosome
28 of 74
What are the chances of two parents with sickle-cell trait having a child with sickle-cell anaemia?
1 in 4 // 25%
29 of 74
During micropropagation of cauliflowers, the number of chromosomes in the cells of some of the plants produced is 36, not 18 as it is in the parent plant...
...
30 of 74
How has the number of chromosomes doubled?
Breakdown of spindle fibres during cell division // Non - disjunction // Chromoatids don't separate
31 of 74
Why are the cauliflower plants that have three of each chromosome type in each of their cells sterile?
Pairing of homologous chromosomes cannot take place // No meiosis // No gametes produced
32 of 74
Which chemical in tobacco smoke contains carcinogens?
Tar
33 of 74
Is the presence or absence of ear lobes an example of continuous or discontinuous variation?
Discontinuous
34 of 74
How might genetic variation be increased in asexually reproducing organisms?
Mutation
35 of 74
What are four sources of variation?
Mutation // Crossing over // Independent assortment // Alleles contributed from each parent
36 of 74
What is meant by the term 'selection pressure'?
The environmental force altering the frequency of alleles in a population?
37 of 74
Why do population numbers remain constant despite the production of large numbers of offspring?
Predation // Competition // Carrying capacity is reached
38 of 74
What is meant by 'geographical isolation'?
When a physical barrier such as a mountain prevents two populations from interbreeding
39 of 74
What is the term used to describe the mother that receives a transplanted embryo?
Surrogate
40 of 74
Why would it be undesirable to produce all farm animals by cloning?
No variation
41 of 74
What is one advantage of cloning animals?
Production of single indentical genetic line of cells with desirable characteristics to maintain genetic stocks
42 of 74
What is one medical application of tissue culture?
Skin graft // Organs for transplantation
43 of 74
Why are sterile conditions necessary in micropropagation?
To prevent fungal growth
44 of 74
What is the process by which totipotent cells develop into root and shoot cells?
Differentiation
45 of 74
What are two advantages of micropropagation for large suppliers such as supermarkers?
Uniform crop // storage // transport
46 of 74
What two phrases summarise the disadvantages of micropropagation?
Sterile conditions // Genetically unstable
47 of 74
What events must take place once the replacement gene is inside the lung cell for the treatment to be successful?
Get into nucleus // Join the DNA of the cells // Protein synthesis // Reinserted into membrane
48 of 74
The bacterium E.coli is widely distributed and capable of exchanging genetic material with other types of bacteria // Why do some scientists consider that the use of recombinant DNA could be dangerous?
A recombinant gene might pass from the organism it was placed in, into a completely different organism // A virus might transfer genes for herbicide resistance from a crop plant to a weed
49 of 74
........
Genetically modified bacteria often have antibiotic resistance maker genes added // This antibiotic resistance could be transferred to harmful bacteria
50 of 74
What is one advantage of the reverse transcriptase technique?
Contains only the gene required // not unwanted gene // Doesn't carry junk DNA or introns // Process doesn't produce a variety of other fragments which need to be screened out
51 of 74
Why are gene markers necessary?
To show which bacterial cells have taken up the plasmid
52 of 74
What is the main concern regarding the pollen of GM crops?
Pollen may be transferred to other plants // Introduce features such as herbicide resistance which could be detrimental if transferred to weed species
53 of 74
What is the enzyme used to cut the DNA?
Restriction endonuclease
54 of 74
What type of bond is broken when DNA strands are separated in the PCR?
Hydrogen
55 of 74
Why is it important that the fragments of DNA used in PCR are not contaminated with any other biological material?
Biological contaminants may contain DNA and this DNA would be copied
56 of 74
Why do forensic scientists often use PCR when producing a genetic fingerprint?
To increase the quantity of DNA because the sample obtained from a crime scene might be very small
57 of 74
What is meant by 'germ therapy'?
Replacing defective gene with a healthy gene in the fertilised egg
58 of 74
Why do carnivores have a much higher secondary productivity than herbivores?
A protein rich diet is more readily and efficiently digested // No energy consuming symbionts in the digestive tract // faeces contain less undigested matter as there is no cellulose in the diet
59 of 74
What is the main difference between primary and secondary succession?
Primary - the introduction of plants and animals into an area that has not previously supported a community // Secondary - the reintroduction of organisms into an area previously occupied but perhaps destroyed by fire
60 of 74
What is the plant type found in a climax community?
Tree (e.g oak)
61 of 74
How are some bacteria resistant to penicillin?
They produce the enzyme PENICILLINASE which makes penicillin ineffective
62 of 74
What is the main disadvantage of interbreeding, in genetic terms?
Increases the chances of two harmful recessive genes combining
63 of 74
What are three main reasons for the decline in numbers of large mammals such as gorillas and tigers?
Loss of habitat // Over-hunting by humans // Competition from introduced species
64 of 74
Why does yield progressively decline if the same crops are grown in the same field year after year?
Mineral depletion // Increase in pests // Increase in disease
65 of 74
What are three consequences of deforestation?
Climate change // Soil erosion // Destruction of natural habitats
66 of 74
How does deforestation contribute to soil erosion?
Lack of roots binding soil together // Resulting in rainfall washing the soil away
67 of 74
What is a crop used to manufacture biofuel?
Oil seed ****
68 of 74
Which country is the world leader in the use of biofuels?
Brazil
69 of 74
What is the main technical problem associated with the production of biofuels?
Pre-treatment of cellulose prior to fermentation
70 of 74
What are two measures that can be enforced to reduce overfishing?
QUOTAS // Restricting net mesh size // Limits to catches // Restricted times of year for fishing
71 of 74
What are two substances added to fish stocks that can cause potential problems to the environment?
Antibiotics // Pesticides
72 of 74
What are two reasons for the increase in carbon dioxide in the atmosphere?
Burning of fossil fuels // Deforestation
73 of 74
What must farmers do to comply with regulations to reduce levels of nitrate in waterways?
Restrict the quantity of fertiliser added to soil // Only apply fertiliser when crops are growing // Leave 10 metre strop between land and waterway
74 of 74

Other cards in this set

Card 2

Front

What are two structures which produce secretions that aid sperm mobility?

Back

Seminal vesicle // Prostate gland

Card 3

Front

Why is the middle piece of the sperm packed with mitochondria?

Back

Preview of the front of card 3

Card 4

Front

What is the function of the Sertoli cells?

Back

Preview of the front of card 4

Card 5

Front

What is the function of the interstitial cells?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all DNA, genetics and evolution resources »