Lunularia cruciata is a primitive plant．Its body consists of a flattened sheet of photosynthetic tissue called a thallus． Fig． 5.1 shows L．cruciata with two different types of reproductive structure，labelled $$$\mathbf{A}$$$ and $$$\mathbf{B}$$$ ，on its surface． Fig． 5.1 （a）Structures $$$\mathbf{A}$$$ and $$$\mathbf{B}$$$ and the thallus of $$$L$$$ ．cruciata are haploid． Explain what is meant by haploid． ............................................................................................................................................... . ............................................................................................................................................... . ............................................................................................................................................... . ......................................................................................................................................... ［2］

Biology

IGCSE&ALevel

CAIE

Exam No：9700_w24_qp_43 Year：2024 Question No：5(a)

Answer:

5.1.1.1 DNA

5.1.1.2 histone proteins

5.1.1.3 sister chromatids

5.1.1.4 centromere

5.1.1.5 telomeres

5.1.2.1 growth of multicellular organisms

5.1.2.2 replacement of damaged or dead cells

5.1.2.3 repair of tissues by cell replacement

5.1.2.4 asexual reproduction

5.1.3.1 interphase (growth in G1 and G2 phases and DNA replication in S phase)

5.1.3.2 mitosis

5.1.3.3 cytokinesis

5.1.4 outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication

5.1.5 outline the role of stem cells in cell replacement and tissue repair by mitosis

5.1.6 explain how uncontrolled cell division can result in the formation of a tumour