Question 1
Which statement describes asexual reproduction?
- Two parents produce offspring that are genetically different from each other
- One parent produces offspring that are genetically identical to it
- Two gametes fuse to form a zygote
- One parent produces gametes that fuse with each other
Show mark scheme for question 1
Answer: B (1)
Question 2
The table gives information about the reproduction of four organisms. (a) Identify the two organisms that reproduce asexually. [2] (b) Give one reason for your answer. [1]
| Organism | How it reproduces |
|---|---|
| P | A bacterial cell divides into two cells. The two cells are the same as the parent cell. |
| Q | A male and a female frog release gametes into the water. The gametes fuse. |
| R | A strawberry plant grows a runner and a new plantlet forms at the end of the runner. |
| S | Pollen from one tomato plant lands on the stigma of another tomato plant. |
Show mark scheme for question 2
- (a) P (1)
- R (1)
- (b) only one parent involved / no gametes fuse / offspring genetically identical (1)
Question 3
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanA farmer grows a crop of potato plants. Each new potato plant is grown from a tuber of a parent plant. (a) Describe two advantages to the farmer of growing the crop by asexual reproduction. [2] (b) Describe two disadvantages of growing the crop by asexual reproduction. [2]
Show mark scheme for question 3
- (a) all plants have the same desirable features / uniform crop / known yield and quality (1)
- quick / cheap / no pollination needed / many plants produced (1) allow only one parent needed
- (b) no genetic variation, so all the plants are susceptible to the same disease or pest (1) allow whole crop could be lost
- no variation so cannot produce new varieties / cannot adapt to changed conditions (1) ignore 'less yield'
- Max 2 for (a) and max 2 for (b)
Question 4
Which statement defines fertilisation?
- The transfer of pollen grains from an anther to a stigma
- The production of offspring from one parent
- The fusion of the nuclei of gametes
- The division of a cell into two identical cells
Show mark scheme for question 4
Answer: C (1)
Question 5
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanThe nucleus of a body cell of an animal contains 14 chromosomes. (a) State the number of chromosomes in the nucleus of a gamete of this animal. [1] (b) State the word used to describe the nucleus of a gamete. [1] (c) Two gametes fuse to form a zygote. State the number of chromosomes in the nucleus of the zygote and the word used to describe this nucleus. [2]
Show mark scheme for question 5
- (a) 7 (1)
- (b) haploid (1)
- (c) 14 (1)
- diploid (1)
Question 6
Supplement (what this means)
Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels meanDiscuss the advantages and disadvantages of sexual reproduction to a population of a species in the wild.
Show mark scheme for question 6
- advantage: offspring show genetic variation / are genetically different (1)
- if the environment changes / new disease appears, some individuals may survive (1) allow better able to adapt / natural selection
- disadvantage: two parents are needed / must find a mate (1)
- takes more time and energy / fewer offspring / population grows more slowly (1)
- Max 4